6l2a
A mutant form of M. tb toxin MazEF-mt1
Structural highlights
FunctionMAZF9_MYCTU Toxic component of a type II toxin-antitoxin (TA) module. Upon expression in E.coli and M.smegmatis inhibits cell growth and colony formation. Its toxic effect is neutralized by coexpression with cognate antitoxin MazE9. Acts as an mRNA interferase, specifically cleaving between U and C in UAC sequences. May cleave its cognate antitoxin's gene (PubMed:25608501). In E.coli expression with non-cognate antitoxins VapB27 and VapB40 partially neutralizes the toxin.[1] [2] [3] [4] [5] Publication Abstract from PubMedToxin-antitoxin (TA) systems, which regulate many important cellular processes, are abundantly present in prokaryotic organisms. MazEF is a common type of TA system implicated in the formation of "persisters cells" of the pathogen Mycobacterium tuberculosis, which contains 10 such systems. However, the exact function and inhibition mode of each MazF protein are not quite understood. Here, we report four high-resolution crystal structures of MazF-mt1 in various forms, including one in complex with MazE-mt1. The toxin displayed two unique interlocked loops that allow the formation of a tight dimer. These loops would open upon interacting with the MazE-mt1 antitoxin mediated by the last two helices of MazE-mt1. With our structure-based design, a mutant that could bind to the antitoxin with an enhanced affinity was produced. Combined crystallographic and biochemical studies further revealed that the binding affinity of MazE-mt1 to MazF-mt1 was mainly attributed to its alpha3 helical region, while the terminal helix eta1 contributes very little or even negatively to the association of the pair, in stark contrast to the MazEF-mt9 system. This study provides structural insight into the binding mode and the inhibition mechanism of the MazE/F-mt1 TA pair, which may reflect the functional differences between different TA systems. Conserved Conformational Changes in the Regulation of Mycobacterium tuberculosis MazEF-mt1.,Chen R, Zhou J, Sun R, Du C, Xie W ACS Infect Dis. 2020 Jul 10;6(7):1783-1795. doi: 10.1021/acsinfecdis.0c00048., Epub 2020 Jun 16. PMID:32485099[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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