A microorganism's response to a harsh environment is characterized by genome-wide changes in gene expression orchestrated by factors that exert a global influence over transcription. These factors are important virulence determinants in pathogenic bacteria because they control the cell's response to the bacteriocidal conditions, such as oxidative stress, imposed by the host's immune systems. A protein from Bacillus subtilis, Spx, both negatively and positively controls transcription over a genome-wide scale in response to oxidative stress. Spx is conserved among low GC Gram-positive bacteria, bears a CXXC motif resembling an active site found in redox factors such as thioredoxin, and is controlled proteolytically by the ATP-dependent protease, C1pXP. In an oxidative environment, Spx affects transcription by interacting with the C-terminal domain of the RNA polymerase (RNAP) alpha subunit (alphaCTD), but it does not itself bind to DNA. The goal of the proposed project is to understand how Spx exerts both negative and positive transcriptional control, and how Spx concentration is regulated. The hypothesis that Spx competes for sites on alphaCTD that are targeted by transcription activators will be tested by conducting mutational analysis to identify activator and Spx interaction surfaces on alphaCTD. Spx-dependent positive control will be studied by determining the composition of the Spx-RNAP transcription complex using DNA-protein crosslinking and suppressor analysis. To further understand the redox control of Spx, the activation and repression activities of mutant versions having residue substitutions in the CXXC motif will be analyzed by in vitro transcription experiments. Thiol-specific reagents and mass spectrometry will be used to identify putative modifications of the Cys residues in the active form of Spx. The transcriptional control of the oxidative stress-induced spx gene will be studied by identifying both cis-acting and trans-acting regulatory factors. Spx proteolytic control will be studied by determining if the Zn-finger domain of the C1pX subunit of C1pXP is the site of redoxdependent regulation. The effects of oxidants on Zn release and C1pXP activity will be determined in vitro.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM045898-16
Application #
7216693
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Anderson, James J
Project Start
1992-02-01
Project End
2009-03-31
Budget Start
2007-04-01
Budget End
2008-03-31
Support Year
16
Fiscal Year
2007
Total Cost
$353,189
Indirect Cost
Name
Oregon Health and Science University
Department
Engineering (All Types)
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Birch, Cierra A; Davis, Madison J; Mbengi, Lea et al. (2017) Exploring the Amino Acid Residue Requirements of the RNA Polymerase (RNAP) ? Subunit C-Terminal Domain for Productive Interaction between Spx and RNAP of Bacillus subtilis. J Bacteriol 199:
Barendt, Skye; Birch, Cierra; Mbengi, Lea et al. (2016) Evidence that Oxidative Stress Induces spxA2 Transcription in Bacillus anthracis Sterne through a Mechanism Requiring SpxA1 and Positive Autoregulation. J Bacteriol 198:2902-2913
Chan, Chio Mui; Hahn, Erik; Zuber, Peter (2014) Adaptor bypass mutations of Bacillus subtilis?spx suggest a mechanism for YjbH-enhanced proteolysis of the regulator Spx by ClpXP. Mol Microbiol 93:426-38
Nakano, Michiko M; Kominos-Marvell, Wren; Sane, Bhagyashree et al. (2014) spxA2, encoding a regulator of stress resistance in Bacillus anthracis, is controlled by SaiR, a new member of the Rrf2 protein family. Mol Microbiol 94:815-27
Lin, Ann A; Walthers, Don; Zuber, Peter (2013) Residue substitutions near the redox center of Bacillus subtilis Spx affect RNA polymerase interaction, redox control, and Spx-DNA contact at a conserved cis-acting element. J Bacteriol 195:3967-78
Chan, Chio Mui; Garg, Saurabh; Lin, Ann A et al. (2012) Geobacillus thermodenitrificans YjbH recognizes the C-terminal end of Bacillus subtilis Spx to accelerate Spx proteolysis by ClpXP. Microbiology 158:1268-78
Lin, Ann A; Zuber, Peter (2012) Evidence that a single monomer of Spx can productively interact with RNA polymerase in Bacillus subtilis. J Bacteriol 194:1697-707
Zuber, Peter; Chauhan, Shefali; Pilaka, Praseeda et al. (2011) Phenotype enhancement screen of a regulatory spx mutant unveils a role for the ytpQ gene in the control of iron homeostasis. PLoS One 6:e25066
Kommineni, Sushma; Garg, Saurabh K; Chan, Chio Mui et al. (2011) YjbH-enhanced proteolysis of Spx by ClpXP in Bacillus subtilis is inhibited by the small protein YirB (YuzO). J Bacteriol 193:2133-40
Nakano, Michiko M; Lin, Ann; Zuber, Cole S et al. (2010) Promoter recognition by a complex of Spx and the C-terminal domain of the RNA polymerase alpha subunit. PLoS One 5:e8664

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