the extracytoplasmic domain of the mycobacterium tuberculosis serthr kinase pknb binds specific muropeptides and is required for pknb localization结核分枝杆菌的extracytoplasmic域serthr激酶pknb pknb需要结合具体muropeptides和本地化.pdf

The Extracytoplasmic Domain of the Mycobacterium tuberculosis Ser/Thr Kinase PknB Binds Specific Muropeptides and Is Required for PknB Localization 1 2 2 2 2 1 Mushtaq Mir , Jinkeng Asong , Xiuru Li , Jessica Cardot , Geert-Jan Boons , Robert N. Husson * 1 Division of Infectious Diseases, Children’s Hospital Boston and Harvard Medical School, Boston, Massachusetts, United States of America, 2 Department of Chemistry and the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America Abstract The Mycobacterium tuberculosis Ser/Thr kinase PknB has been implicated in the regulation of cell growth and morphology in this organism. The extracytoplasmic domain of this membrane protein comprises four penicillin binding protein and Ser/Thr kinase associated (PASTA) domains, which are predicted to bind stem peptides of peptidoglycan. Using a comprehensive library of synthetic muropeptides, we demonstrate that the extracytoplasmic domain of PknB binds muropeptides in a manner dependent on the presence of specific amino acids at the second and third positions of the stem peptide, and on the presence of the sugar moiety N-acetylmuramic acid linked to the peptide. We further show that PknB localizes strongly to the mid-cell and also to the cell poles, and that the extracytoplasmic domain is required for PknB localization. In contrast to strong growth stimulation by conditioned medium, we observe no growth stimulation of M. tuberculosis by a synthetic muropeptide with high affinity for the PknB PASTAs. We do find a moderate effect of a high affinity peptide on resuscitation of dormant cells. While the PASTA domains of PknB may play a role in stimulating growth by binding