Biochemical and physiological characterization of the GTP-binding protein Obg of Mycobacterium tuberculosis

BMC Microbiology

Research Article

Sankaralingam Saikolappan¹  Smitha J Sasindran¹  Subramanian Dhandayuthapani¹  Virginia L Scofield¹ 

[1] Regional Academic Health Center and Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 78541, Edinburg, Texas, USA;

关键词: Tuberculosis;    Membrane Fraction;    Cetyl Trimethyl Ammonium Bromide;    Tuberculosis H37Rv;    Magnesium Acetate;   

DOI  :  10.1186/1471-2180-11-43

 received in 2010-08-18, accepted in 2011-02-25,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundObg is a highly conserved GTP-binding protein that has homologues in bacteria, archaea and eukaryotes. In bacteria, Obg proteins are essential for growth, and they participate in spore formation, stress adaptation, ribosome assembly and chromosomal partitioning. This study was undertaken to investigate the biochemical and physiological characteristics of Obg in Mycobacterium tuberculosis, which causes tuberculosis in humans.ResultsWe overexpressed M. tuberculosis Obg in Escherichia coli and then purified the protein. This protein binds to, hydrolyzes and is phosphorylated with GTP. An anti-Obg antiserum, raised against the purified Obg, detects a 55 kDa protein in immunoblots of M. tuberculosis extracts. Immunoblotting also discloses that cultured M. tuberculosis cells contain increased amounts of Obg in the late log phase and in the stationary phase. Obg is also associated with ribosomes in M. tuberculosis, and it is distributed to all three ribosomal fractions (30 S, 50 S and 70 S). Finally, yeast two-hybrid analysis reveals that Obg interacts with the stress protein UsfX, indicating that M. tuberculosis Obg, like other bacterial Obgs, is a stress related protein.ConclusionsAlthough its GTP-hydrolyzing and phosphorylating activities resemble those of other bacterial Obg homologues, M. tuberculosis Obg differs from them in these respects: (a) preferential association with the bacterial membrane; (b) association with all three ribosomal subunits, and (c) binding to the stress protein UsfX, rather than to RelA. Generation of mutant alleles of Obg of M. tuberculosis, and their characterization in vivo, may provide additional insights regarding its role in this important human pathogen.

【 授权许可】

Unknown   
© Sasindran et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.