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Title: Crystal structure of Bacillus anthracis virulence regulator AtxA and effects of phosphorylated histidines on multimerization and activity

The Bacillus anthracis virulence regulator AtxA controls transcription of the anthrax toxin genes and capsule biosynthesis operon. AtxA activity is elevated during growth in media containing glucose and CO2/bicarbonate, and there is a positive correlation between the CO2/bicarbonate signal, AtxA activity, and homomultimerization. AtxA activity is also affected by phosphorylation at specific histidines. We show that AtxA crystallizes as a dimer. Distinct folds associated with predicted DNA-binding domains (HTH1 and HTH2) and phosphoenolpyruvate: carbohydrate phosphotransferase system-regulated domains (PRD1 and PRD2) are apparent. We tested AtxA variants containing single and double phosphomimetic (His → Asp) and phosphoablative (His → Ala) amino acid changes for activity in B. anthracis cultures and for protein-protein interactions in cell lysates. Reduced activity of AtxA H199A, lack of multimerization and activity of AtxAH379D variants, and predicted structural changes associated with phosphorylation support a model for control of AtxA function. We propose that (1) in the AtxA dimer, phosphorylation of H199 in PRD1 affects HTH2 positioning, influencing DNA-binding; and (2) phosphorylation of H379 in PRD2 disrupts dimer formation. In conclusion, the AtxA structure is the first reported high-resolution full-length structure of a PRD-containing regulator and can serve as a model for proteins of this family, especially thosemore » that link virulence to bacterial metabolism.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [1]
  1. Univ. of Texas Health Science Center at Houston, Houston, TX (United States). Dept. of Microbiology and Molecular Genetics
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Structural Genomics of Infectious Diseases; Argonne National Lab. (ANL), Argonne, IL (United States). Biosciences Division
Publication Date:
OSTI Identifier:
1280877
Grant/Contract Number:
AC02-06CH11357; HHSN272200700058C; HHSN272201200026C; R01 AI033537; 1 T32 AI065396
Type:
Accepted Manuscript
Journal Name:
Molecular microbiology
Additional Journal Information:
Journal Volume: 95; Journal Issue: 3; Journal ID: ISSN 0950-382X
Publisher:
Wiley
Research Org:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES transcription; phosphotransferase; AtxA; phosphorylation; virulence; anthrax