Email updates

Keep up to date with the latest news and content from BMC Microbiology and BioMed Central.

Open Access Research article

Mycobacterium tuberculosis Rv1096 protein: gene cloning, protein expression, and peptidoglycan deacetylase activity

Shufeng Yang12, Fei Zhang1, Jian Kang1, Wenli Zhang1, Guoying Deng12, Yi Xin3 and Yufang Ma14*

Author Affiliations

1 Department of Biochemistry and Molecular Biology, Dalian Medical University, 9 W Lushun South Road, Dalian 116044, China

2 Department of Microbiology, Dalian Medical University, Dalian 116044, China

3 Department of Biotechnology, Dalian Medical University, Dalian 116044, China

4 Liaoning Provincial Core Lab of Glycobiology and Glycoengineering, Dalian 116044, China

For all author emails, please log on.

BMC Microbiology 2014, 14:174  doi:10.1186/1471-2180-14-174

Published: 30 June 2014

Abstract

Background

Many bacteria modulate and evade the immune defenses of their hosts through peptidoglycan (PG) deacetylation. The PG deacetylases from Streptococcus pneumonia, Listeria monocytogenes and Lactococcus lactis have been characterized. However, thus far, the PG deacetylase of Mycobacterium tuberculosis has not been identified.

Results

In this study, we cloned the Rv1096 gene from the M. tuberculosis H37Rv strain and expressed Rv1096 protein in both Escherichia coli and M. smegmatis. The results showed that the purified Rv1096 protein possessed metallo-dependent PG deacetylase activity, which increased in the presence of Co2+. The kinetic parameters of the PG deacetylase towards M. smegmatis PG as a substrate were as follows: Km, 0.910 ± 0.007 mM; Vmax, 0.514 ± 0.038 μMmin-1; and Kcat = 0.099 ± 0.007 (S-1). Additionally, the viability of M. smegmatis in the presence of over-expressed Rv1096 protein was 109-fold higher than that of wild-type M. smegmatis after lysozyme treatment. Additionally, light microscopy and scanning electron microscopy showed that in the presence of over-expressed Rv1096 protein, M. smegmatis kept its regular shape, with an undamaged cell wall and smooth surface. These results indicate that Rv1096 caused deacetylation of cell wall PG, leading to lysozyme resistance in M. smegmatis.

Conclusion

We have determined that M. tuberculosis Rv1096 is a PG deacetylase. The PG deacetylase activity of Rv1096 contributed to lysozyme resistance in M. smegmatis. Our findings suggest that deacetylation of cell wall PG may be involved in evasion of host immune defenses by M. tuberculosis.

Keywords:
Mycobacterium tuberculosis; Cell wall; Rv1096; Peptidoglycan deacetylase; Lysozyme