A putative aminotransferase gene, cc3143 (aptA), from Caulobacter crescentus was screened by bioinformatical tools and overexpressed in E. coli, and the substrate specificity of the aminotransferase was investigated. AptA showed high activity for short-chain beta-amino acids. It showed the highest activity for 3-amino-n-butyric acid. It showed higher activity toward aromatic amines than aliphatic amines. The 3D model of the aminotransferase was constructed by homology modeling using a dialkylglycine decarboxylase PDB ID: 1DGE) as a template. Then, the aminotransferase was rationally redesigned to increase the activity for 3-amino- 3-phenylpropionic acid. The mutants N285A and V227G increased the relative activity for 3-amino-3-phenylpropionic acid to 3-amino-n-butyric acid by 11-fold and 3-fold, respectively, over that of wild type.
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Appl Environ Microbiol
December 2024
Biology Department, San Diego State University, San Diego, California, USA.
Unlabelled: Many species of proteobacterial methane-consuming bacteria (methanotrophs) form a hauberk-like envelope represented by a surface (S-) layer protein (SLP) matrix. While several proteins were predicted to be associated with the cell surface, the composition and function of the hauberk matrix remained elusive. Here, we report the identification of the genes encoding the hauberk-forming proteins in two gamma-proteobacterial (Type I) methanotrophs, 5GB1 (EQU24_15540) and 20Z (MEALZ_0971 and MEALZ_0972).
View Article and Find Full Text PDFNat Commun
December 2024
Department of Biophysics & Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Most bacteria lack membrane-enclosed organelles and rely on macromolecular scaffolds at different subcellular locations to recruit proteins for specific functions. Here, we demonstrate that the optogenetic CRY2-CIB1 system from Arabidopsis thaliana can be used to rapidly direct proteins to different subcellular locations with varying efficiencies in live Escherichia coli cells, including the nucleoid, the cell pole, the membrane, and the midcell division plane. Such light-induced re-localization can be used to rapidly inhibit cytokinesis in actively dividing E.
View Article and Find Full Text PDFElife
December 2024
Howard Hughes Medical Institute, Stanford University, Stanford, United States.
Defining the cellular factors that drive growth rate and proteome composition is essential for understanding and manipulating cellular systems. In bacteria, ribosome concentration is known to be a constraining factor of cell growth rate, while gene concentration is usually assumed not to be limiting. Here, using single-molecule tracking, quantitative single-cell microscopy, and modeling, we show that genome dilution in cells arrested for DNA replication limits total RNA polymerase activity within physiological cell sizes across tested nutrient conditions.
View Article and Find Full Text PDFNucleic Acids Res
December 2024
Institute of Microbiology, Friedrich Schiller University, 07743 Jena, Germany.
Small RNAs (sRNAs) play a crucial role in modulating target gene expression through short base-pairing interactions and serve as integral components of many stress response pathways and regulatory circuits in bacteria. Transcriptome analyses have facilitated the annotation of dozens of sRNA candidates in the ubiquitous environmental model bacterium Caulobacter crescentus, but their physiological functions have not been systematically investigated so far. To address this gap, we have established CauloSOEP, a multi-copy plasmid library of C.
View Article and Find Full Text PDFiScience
December 2024
Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia.
Disulfide bond (Dsb) oxidoreductases involved in oxidative protein folding govern bacterial survival and virulence. Over the past decade, oligomerization has emerged as a potential factor that dictates oxidoreductase activities. To investigate the role of oligomerization, we studied three Dsb-like ScsC oxidoreductases involved in copper resistance: the monomeric StScsC, and the trimeric PmScsC and CcScsC.
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