The target range of a bacterial secretion system can be defined by effector substrate specificity or by the efficacy of effector delivery. Here, we report the crystal structure of Tse1, a type VI secretion (T6S) bacteriolytic amidase effector from Pseudomonas aeruginosa. Consistent with its role as a toxin, Tse1 has a more accessible active site than related housekeeping enzymes. The activity of Tse1 against isolated peptidoglycan shows its capacity to act broadly against Gram-negative bacteria and even certain Gram-positive species. Studies with intact cells indicate that Gram-positive bacteria can remain vulnerable to Tse1 despite cell wall modifications. However, interbacterial competition studies demonstrate that Tse1-dependent lysis is restricted to Gram-negative targets. We propose that the previously observed specificity for T6S against Gram-negative bacteria is a consequence of high local effector concentration achieved by T6S-dependent targeting to its site of action rather than inherent effector substrate specificity.
Structure of a peptidoglycan amidase effector targeted to Gram-negative bacteria by the type VI secretion system.
Seemay Chou,N. K. Bui,Alistair B. Russell,Katrina W. Lexa,Taylor E. Gardiner,Michele LeRoux,W. Vollmer,J. D. Mougous
Published 2012 in Cell Reports
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- Publication year
2012
- Venue
Cell Reports
- Publication date
2012-06-28
- Fields of study
Biology, Medicine, Chemistry
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- Source metadata
Semantic Scholar, PubMed
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