Latency in Mycobacterium tuberculosis poses a barrier in its complete eradication. Overexpression of certain genes is one of the factors that help these bacilli survive inside the host during latency. Among these genes, rel, which leads to the expression of Rel protein, plays an important role by synthesizing the signaling molecule ppGpp using GDP and ATP as substrates, thereby changing bacterial physiology. In Gram-negative bacteria, the protein is thought to be activated in vivo in the presence of ribosome by sensing uncharged tRNA. In the present report, we show that Rel protein from Mycobacterium smegmatis, which is highly homologous to M. tuberculosis Rel, is functional even in the absence of ribosome and uncharged tRNA. From the experiments presented here, it appears that the activity of Rel Msm is regulated by the domains present at the C terminus, as the deletion of these domains results in higher synthesis activity, with little change in hydrolysis of ppGpp. However, in the presence of tRNA, though the synthesis activity of the full-length protein increases to a certain extent, the hydrolysis activity undergoes drastic reduction. Fulllength Rel undergoes multimerization involving interchain disulfide bonds. The synthesis of pppGpp by the full-length protein is enhanced in the reduced environment in vitro, whereas the hydrolysis activity does not change significantly. Mutations of cysteines to serines result in monomerization with a simultaneous increase in the synthesis activity. Finally, it has been possible to identify the unique cysteine, of six present in Rel, required for tRNA-mediated synthesis of ppGpp.Keywords: Rel protein; stringent response; ppGpp; multimerization; Rel domains Mycobacterium tuberculosis can be categorized as one of the most successful among human pathogens as several decades of research have not yet been able to completely eradicate tuberculosis (TB), the deadly disease caused by this organism. The major barrier toward complete cure from mycobacterial infection is the unique feature, termed ''latency,'' that these bacteria undergo on infection, leading to overexpression of genes that enable the survival of the pathogen within host organisms under oxygen-(Wayne and Hayes 1996) and nutrient-deprived (Nyka 1974) conditions. Such latent bacteria have been known to be confined in calcified lesions, termed ''granulomas,'' which enable the dormant bacteria to resist conventional antibiotics used against active bacilli. It had been proposed that the morphology and hydrophobicity of the in vivo persistors can be mimicked in laboratory cultures by starving bacteria in vitro (Nyka 1974). Under such stress conditions, adaptation to the Reprint requests to: Dipankar Chatterji, Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India; e-mail: dipankar@mbu.iisc.ernet.in; fax: +91-80-23600535.Abbreviations: pppGpp, guanosine 39-diphosphate 59-triphosphate; ppGpp, guanosine 39, 59-bis(diphosphate); IPTG, isopropyl b-D-1-thiogalactopyranoside; Ni-NTA, nickel-nitr...

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Background:Quality of life is an important aspect in diabetes because poor quality of life leads to diminished self-care, which in turn leads to worsened glycemic control, increased risks for complications, and exacerbation of diabetes overwhelming in both the short run and the long run.Aims:The aim of our study is to examine the health-related quality of life of diabetic patients in rural India.Materials and Methods:This case-control study was done among type 2 diabetes mellitus patients attending Medicine Outpatient department of a 780-bedded rural medical college located in central India. We used the World Health Organization Quality of Life Questionnaire — short version (WHOQOL-BREF) to assess quality of life.Results:The HRQOL among diabetics and non-diabetic controls is comparable to each other with bad physical health, bad psychological health, deteriorating social relationships, and bad environmental conditions affecting the HRQOL of both the groups equally. The overall HRQOL of the total study population (cases and controls) was poor.Conclusion:The finding of this study will help in health promotion in rural medical practice in India. It would beckon the much awaited avenue of holistic care of a diabetic patient with equal importance to the mental wellbeing and quality of life, as compared to physical well being.

Holins are phage-encoded small transmembrane proteins that perforate the bacterial cytoplasmic membrane. In most cases, this process allows the phage-encoded peptidoglycan hydrolases to act on the cell wall, resulting in host cell lysis and phage release. We report a detailed functional characterization of Mycobacterium phage D29 gp11 coding for a putative holin that, upon expression, rapidly kills both Escherichia coli and Mycobacterium smegmatis. We dissected Gp11 by making several deletions and expressing them in E. coli. The shortening of Gp11 from its C-terminus results in diminished cytotoxicity and smaller holes. Evidently, the two transmembrane domains (TMDs) present at the N-terminus of Gp11 are incapable of integrating into the cytoplasmic membrane and do not show toxicity. Interestingly, the fusion of two TMDs and a small C-terminal region that bears the coiled-coil motif resulted in restoration of the cell killing ability of the protein. We further show that the second TMD is dispensable in protein toxicity because its deletion does not abolish Gp11-mediated cell death. We conclude that Gp11 C-terminal region is necessary but not sufficient for toxicity. These results shed light on a yet undiscovered role of Gp11 C-terminal region that will help clarify the mechanism of holin-mediated membrane perforation. Finally, we abolish the toxicity of Gp11 using a specific Gly to Asp substitution in the putative loop region of the protein; the mutant protein may help to clarify how holin functions in mycobacteriophage D29.

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