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  1. Article ; Online: Genes Vary Greatly in Their Propensity for Collateral Fitness Effects of Mutations.

    Mehlhoff, Jacob D / Ostermeier, Marc

    Molecular biology and evolution

    2023  Volume 40, Issue 3

    Abstract: Mutations can have deleterious fitness effects when they decrease protein specific activity or decrease active protein abundance. Mutations will also be deleterious when they cause misfolding or misinteractions that are toxic to the cell (i.e., ... ...

    Abstract Mutations can have deleterious fitness effects when they decrease protein specific activity or decrease active protein abundance. Mutations will also be deleterious when they cause misfolding or misinteractions that are toxic to the cell (i.e., independent of whether the mutations affect specific activity and abundance). The extent to which protein evolution is shaped by these and other collateral fitness effects is unclear in part because little is known of their frequency and magnitude. Using deep mutational scanning (DMS), we previously found at least 42% of missense mutations in the TEM-1 β-lactamase antibiotic resistance gene cause deleterious collateral fitness effects. Here, we used DMS to comprehensively determine the collateral fitness effects of missense mutations in three genes encoding the antibiotic resistance proteins New Delhi metallo-β-lactamase (NDM-1), chloramphenicol acetyltransferase I (CAT-I), and 2″-aminoglycoside nucleotidyltransferase (AadB). AadB (20%), CAT-I (0.9%), and NDM-1 (0.2%) were less susceptible to deleterious collateral fitness effects than TEM-1 (42%) indicating that genes have different propensities for these effects. As was observed with TEM-1, all the studied deleterious aadB mutants increased aggregation. However, aggregation did not correlate with collateral fitness effects for many of the deleterious mutants of CAT-I and NDM-1. Select deleterious mutants caused unexpected phenotypes to emerge. The introduction of internal start codons in CAT-1 caused loss of the episome and a mutation in aadB made its cognate antibiotic essential for growth. Our study illustrates how the complexity of the cell provides a rich environment for collateral fitness effects and new phenotypes to emerge.
    MeSH term(s) Mutation ; beta-Lactamases/genetics ; Mutation, Missense ; Anti-Bacterial Agents/pharmacology ; Proteins/genetics ; Drug Resistance, Microbial
    Chemical Substances beta-Lactamases (EC 3.5.2.6) ; Anti-Bacterial Agents ; Proteins
    Language English
    Publishing date 2023-02-16
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 998579-7
    ISSN 1537-1719 ; 0737-4038
    ISSN (online) 1537-1719
    ISSN 0737-4038
    DOI 10.1093/molbev/msad038
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Fitness and Functional Landscapes of the E. coli RNase III Gene rnc.

    Weeks, Ryan / Ostermeier, Marc

    Molecular biology and evolution

    2023  Volume 40, Issue 3

    Abstract: How protein properties such as protein activity and protein essentiality affect the distribution of fitness effects (DFE) of mutations are important questions in protein evolution. Deep mutational scanning studies typically measure the effects of a ... ...

    Abstract How protein properties such as protein activity and protein essentiality affect the distribution of fitness effects (DFE) of mutations are important questions in protein evolution. Deep mutational scanning studies typically measure the effects of a comprehensive set of mutations on either protein activity or fitness. Our understanding of the underpinnings of the DFE would be enhanced by a comprehensive study of both for the same gene. Here, we compared the fitness effects and in vivo protein activity effects of ∼4,500 missense mutations in the E. coli rnc gene. This gene encodes RNase III, a global regulator enzyme that cleaves diverse RNA substrates including precursor ribosomal RNA and various mRNAs including its own 5' untranslated region (5'UTR). We find that RNase III's ability to cleave dsRNA is the most important determinant of the fitness effects of rnc mutations. The DFE of RNase III was bimodal, with mutations centered around neutral and deleterious effects, consistent with previously reported DFE's of enzymes with a singular physiological role. Fitness was buffered to small effects on RNase III activity. The enzyme's RNase III domain, which contains the RNase III signature motif and all active site residues, was more sensitive to mutation than its dsRNA binding domain, which is responsible for recognition and binding to dsRNA. Differential effects on fitness and functional scores for mutations at highly conserved residues G97, G99, and F188 suggest that these positions may be important for RNase III cleavage specificity.
    MeSH term(s) Escherichia coli/genetics ; Escherichia coli/metabolism ; Ribonuclease III/genetics ; Escherichia coli Proteins/genetics ; Mutation
    Chemical Substances Ribonuclease III (EC 3.1.26.3) ; Escherichia coli Proteins
    Language English
    Publishing date 2023-03-05
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 998579-7
    ISSN 1537-1719 ; 0737-4038
    ISSN (online) 1537-1719
    ISSN 0737-4038
    DOI 10.1093/molbev/msad047
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: A CRISPR-dCas9 System for Assaying and Selecting for RNase III Activity

    Hauk, Pricila / Weeks, Ryan / Ostermeier, Marc

    The CRISPR journal

    2022  Volume 6, Issue 1, Page(s) 43–51

    Abstract: Ribonuclease III (RNase III) and RNase III-like ribonucleases have a wide range of important functions and are found in all organisms, yet a simple and high- ... ...

    Abstract Ribonuclease III (RNase III) and RNase III-like ribonucleases have a wide range of important functions and are found in all organisms, yet a simple and high-throughput
    MeSH term(s) Humans ; Escherichia coli/genetics ; Ribonuclease III/genetics ; Ribonuclease III/metabolism ; CRISPR-Cas Systems/genetics ; Gene Editing ; RNA
    Chemical Substances Ribonuclease III (EC 3.1.26.3) ; RNA (63231-63-0)
    Language English
    Publishing date 2022-12-09
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 3017891-5
    ISSN 2573-1602 ; 2573-1599
    ISSN (online) 2573-1602
    ISSN 2573-1599
    DOI 10.1089/crispr.2022.0041
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: A bacterial dual positive and negative selection system for dCas9 activity.

    Spisak, Shaun / O'Brien, Brett / Ostermeier, Marc

    PloS one

    2022  Volume 17, Issue 6, Page(s) e0269270

    Abstract: The engineering of switchable or activatable dCas9 proteins would benefit from a single system for both positive and negative selection of dCas9 activity. Most systems that are used to interrogate dCas9 libraries use a fluorescent protein screen or an ... ...

    Abstract The engineering of switchable or activatable dCas9 proteins would benefit from a single system for both positive and negative selection of dCas9 activity. Most systems that are used to interrogate dCas9 libraries use a fluorescent protein screen or an antibiotic selection for active dCas9 variants. To avoid some of the limitations of these systems, we have developed a single system capable of selecting for either active or inactive dCas9 variants. E. coli expressing active dCas9 variants are isolated in the positive selection system through growth in the presence of ampicillin. The negative selection can isolate cells lacking dCas9 activity through two separate mechanisms: growth in M9 minimal media or growth in media containing streptomycin. This system is capable of enriching for rare dCas9 variants up to 9,000-fold and possesses potential utility in directed evolution experiments to create switchable dCas9 proteins.
    MeSH term(s) CRISPR-Cas Systems ; Escherichia coli/genetics
    Language English
    Publishing date 2022-06-03
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2267670-3
    ISSN 1932-6203 ; 1932-6203
    ISSN (online) 1932-6203
    ISSN 1932-6203
    DOI 10.1371/journal.pone.0269270
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Biological fitness landscapes by deep mutational scanning.

    Mehlhoff, Jacob D / Ostermeier, Marc

    Methods in enzymology

    2020  Volume 643, Page(s) 203–224

    Abstract: Knowledge of the distribution of fitness effects (DFE) of mutations is critical to the understanding of protein evolution. Here, we describe methods for large-scale, systematic measurements of the DFE using growth competition and deep mutational scanning. ...

    Abstract Knowledge of the distribution of fitness effects (DFE) of mutations is critical to the understanding of protein evolution. Here, we describe methods for large-scale, systematic measurements of the DFE using growth competition and deep mutational scanning. We discuss techniques for producing comprehensive libraries of gene variants as well as provide necessary considerations for designing these experiments. Using these methods, we have constructed libraries containing over 18,000 variants, measured fitness effects of these mutations by deep mutational scanning, and verified the presence of fitness effects in individual variants. Our methods provide a high-throughput protocol for measuring biological fitness effects of mutations and the dependence of fitness effects on the environment.
    MeSH term(s) Models, Genetic ; Mutation
    Language English
    Publishing date 2020-05-05
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1557-7988
    ISSN (online) 1557-7988
    DOI 10.1016/bs.mie.2020.04.023
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Engineered protein switches for exogenous control of gene expression.

    Spisak, Shaun / Ostermeier, Marc

    Biochemical Society transactions

    2020  Volume 48, Issue 5, Page(s) 2205–2212

    Abstract: There is an ongoing need in the synthetic biology community for novel ways to regulate gene expression. Protein switches, which sense biological inputs and respond with functional outputs, represent one way to meet this need. Despite the fact that there ... ...

    Abstract There is an ongoing need in the synthetic biology community for novel ways to regulate gene expression. Protein switches, which sense biological inputs and respond with functional outputs, represent one way to meet this need. Despite the fact that there is already a large pool of transcription factors and signaling proteins available, the pool of existing switches lacks the substrate specificities and activities required for certain applications. Therefore, a large number of techniques have been applied to engineer switches with novel properties. Here we discuss some of these techniques by broadly organizing them into three approaches. We show how novel switches can be created through mutagenesis, domain swapping, or domain insertion. We then briefly discuss their use as biosensors and in complex genetic circuits.
    MeSH term(s) Allosteric Site ; Animals ; Biochemical Phenomena ; Biosensing Techniques/methods ; DNA/chemistry ; Dimerization ; Gene Expression ; Gene Expression Regulation ; Gene Regulatory Networks ; Genetic Engineering ; Humans ; Mice ; Mutagenesis ; Mutation ; Protein Domains ; Protein Engineering/methods ; Proteins/genetics ; Signal Transduction ; Substrate Specificity ; Synthetic Biology ; Transcription Factors/metabolism
    Chemical Substances Proteins ; Transcription Factors ; DNA (9007-49-2)
    Language English
    Publishing date 2020-10-20
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S. ; Review
    ZDB-ID 184237-7
    ISSN 1470-8752 ; 0300-5127
    ISSN (online) 1470-8752
    ISSN 0300-5127
    DOI 10.1042/BST20200441
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: A bacterial dual positive and negative selection system for dCas9 activity

    Shaun Spisak / Brett O’Brien / Marc Ostermeier

    PLoS ONE, Vol 17, Iss

    2022  Volume 6

    Abstract: The engineering of switchable or activatable dCas9 proteins would benefit from a single system for both positive and negative selection of dCas9 activity. Most systems that are used to interrogate dCas9 libraries use a fluorescent protein screen or an ... ...

    Abstract The engineering of switchable or activatable dCas9 proteins would benefit from a single system for both positive and negative selection of dCas9 activity. Most systems that are used to interrogate dCas9 libraries use a fluorescent protein screen or an antibiotic selection for active dCas9 variants. To avoid some of the limitations of these systems, we have developed a single system capable of selecting for either active or inactive dCas9 variants. E. coli expressing active dCas9 variants are isolated in the positive selection system through growth in the presence of ampicillin. The negative selection can isolate cells lacking dCas9 activity through two separate mechanisms: growth in M9 minimal media or growth in media containing streptomycin. This system is capable of enriching for rare dCas9 variants up to 9,000-fold and possesses potential utility in directed evolution experiments to create switchable dCas9 proteins.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Pervasive Pairwise Intragenic Epistasis among Sequential Mutations in TEM-1 β-Lactamase.

    Gonzalez, Courtney E / Ostermeier, Marc

    Journal of molecular biology

    2019  Volume 431, Issue 10, Page(s) 1981–1992

    Abstract: Interactions between mutations play a central role in shaping the fitness landscape, but a clear picture of intragenic epistasis has yet to emerge. To further reveal the prevalence and patterns of intragenic epistasis, we present a survey of epistatic ... ...

    Abstract Interactions between mutations play a central role in shaping the fitness landscape, but a clear picture of intragenic epistasis has yet to emerge. To further reveal the prevalence and patterns of intragenic epistasis, we present a survey of epistatic interactions between sequential mutations in TEM-1 β-lactamase. We measured the fitness effect of ~12,000 pairs of consecutive amino acid substitutions and used our previous study of the fitness effects of single amino acid substitutions to calculate epistasis for over 8000 mutation pairs. Since sequential mutations are prone to physically interact, we postulated that our study would be surveying specific epistasis instead of nonspecific epistasis. We found widespread negative epistasis, especially in beta-strands, and a high frequency of negative sign epistasis among individually beneficial mutations. Negative epistasis (52%) occurred 7.6 times as frequently as positive epistasis (6.8%). Buried residues experienced more negative epistasis that surface-exposed residues. However, TEM-1 exhibited a couple of hotspots for positive epistasis, most notably L221/ R222 at which many combinations of mutations positively interacted. This study is the first to systematically examine pairwise epistasis throughout an entire protein performing its native function in its native host.
    MeSH term(s) Amino Acid Substitution ; Epistasis, Genetic ; Escherichia coli/chemistry ; Escherichia coli/genetics ; Escherichia coli Infections/microbiology ; Escherichia coli Proteins/chemistry ; Escherichia coli Proteins/genetics ; Evolution, Molecular ; Genetic Fitness ; Humans ; Models, Molecular ; Mutation ; Protein Conformation ; beta-Lactamases/chemistry ; beta-Lactamases/genetics
    Chemical Substances Escherichia coli Proteins ; beta-Lactamases (EC 3.5.2.6) ; beta-lactamase TEM-1 (EC 3.5.2.6)
    Language English
    Publishing date 2019-03-25
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2019.03.020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Thermostability Enhancement of GH 62 α-l-Arabinofuranosidase by Directed Evolution and Rational Design.

    Martins, Manoela / Dos Santos, Alberto M / da Costa, Clauber H S / Canner, Samuel W / Chungyoun, Michael / Gray, Jeffrey J / Skaf, Munir S / Ostermeier, Marc / Goldbeck, Rosana

    Journal of agricultural and food chemistry

    2024  Volume 72, Issue 8, Page(s) 4225–4236

    Abstract: GH 62 arabinofuranosidases are known for their excellent specificity for arabinoxylan of agroindustrial residues and their synergism with endoxylanases and other hemicellulases. However, the low thermostability of some GH enzymes hampers potential ... ...

    Abstract GH 62 arabinofuranosidases are known for their excellent specificity for arabinoxylan of agroindustrial residues and their synergism with endoxylanases and other hemicellulases. However, the low thermostability of some GH enzymes hampers potential industrial applications. Protein engineering research highly desires mutations that can enhance thermostability. Therefore, we employed directed evolution using one round of error-prone PCR and site-saturation mutagenesis for thermostability enhancement of GH 62 arabinofuranosidase from
    MeSH term(s) Enzyme Stability ; Protein Engineering ; Temperature ; Mutagenesis ; Glycoside Hydrolases
    Chemical Substances alpha-N-arabinofuranosidase (EC 3.2.1.55) ; Glycoside Hydrolases (EC 3.2.1.-)
    Language English
    Publishing date 2024-02-14
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241619-0
    ISSN 1520-5118 ; 0021-8561
    ISSN (online) 1520-5118
    ISSN 0021-8561
    DOI 10.1021/acs.jafc.3c08019
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Fitness Effects of Single Amino Acid Insertions and Deletions in TEM-1 β-Lactamase.

    Gonzalez, Courtney E / Roberts, Paul / Ostermeier, Marc

    Journal of molecular biology

    2019  Volume 431, Issue 12, Page(s) 2320–2330

    Abstract: Short insertions and deletions (InDels) are a common type of mutation found in nature and a useful source of variation in protein engineering. InDel events have important consequences in protein evolution, often opening new pathways for adaptation. ... ...

    Abstract Short insertions and deletions (InDels) are a common type of mutation found in nature and a useful source of variation in protein engineering. InDel events have important consequences in protein evolution, often opening new pathways for adaptation. However, much less is known about the effects of InDels compared to point mutations and amino acid substitutions. In particular, deep mutagenesis studies on the distribution of fitness effects of mutations have focused almost exclusively on amino acid substitutions. Here, we present a near-comprehensive analysis of the fitness effects of single amino acid InDels in TEM-1 β-lactamase. While we found InDels to be largely deleterious, partially overlapping deletion-tolerant and insertion-tolerant regions were observed throughout the protein, especially in unstructured regions and at the end of helices. The signal sequence of TEM-1 tolerated InDels more than the mature protein. Most regions of the protein tolerated insertions more than deletions, but a few regions tolerated deletions more than insertions. We examined the relationship between InDel tolerance and a variety of measures to help understand its origin. These measures included evolutionary variation in β-lactamases, secondary structure identity, tolerance to amino acid substitutions, solvent accessibility, and side-chain weighted contact number. We found secondary structure, weighted contact number, and evolutionary variation in class A beta-lactamases to be the somewhat predictive of InDel fitness effects.
    MeSH term(s) Amino Acid Substitution ; Drug Resistance, Bacterial ; Escherichia coli/chemistry ; Escherichia coli/genetics ; Escherichia coli Infections/microbiology ; Escherichia coli Proteins/chemistry ; Escherichia coli Proteins/genetics ; Humans ; INDEL Mutation ; Models, Molecular ; Protein Conformation ; beta-Lactamases/chemistry ; beta-Lactamases/genetics
    Chemical Substances Escherichia coli Proteins ; beta-Lactamases (EC 3.5.2.6) ; beta-lactamase TEM-1 (EC 3.5.2.6)
    Language English
    Publishing date 2019-04-26
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2019.04.030
    Database MEDical Literature Analysis and Retrieval System OnLINE

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