Structure of Microcin J25, a Peptide Inhibitor of Bacterial RNA Polymerase, is a Lassoed Tail
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- 作者：Kelly-Anne Wilson ; Markus Kalkum ; Jennifer Ottesen ; Julia Yuzenkova ; Brian T. Chait ; Robert Landick ; Tom Muir ; Konstantin Severinov ; and Seth A. Darst
- 刊名：Journal of the American Chemical Society
- 出版年：2003
- 出版时间：October 15, 2003
- 年：2003
- 卷：125
- 期：41
- 页码：12475 - 12483
- 全文大小：501K
- 年卷期：v.125,no.41(October 15, 2003)
- ISSN：1520-5126
文摘
Microcin J25 (MccJ25) is a 21-amino acid peptide inhibitor active against the DNA-dependentRNA polymerase of Gram negative bacteria. Previously, the structure of MccJ25 was reported to be ahead-to-tail circle, cyclo(-G1GAGHVPEYF10VGIGTPISFY20G-). On the basis of biochemical studies, massspectrometry, and NMR, we show that this structure is incorrect, and that the peptide has an extraordinarystructural fold. MccJ25 contains an internal lactam linkage between the 
-amino group of Gly1 and the
-carboxyl of Glu8. The tail (Tyr9-Gly21) passes through the ring (Gly1-Glu8), with Phe19 and Tyr20straddling each side of the ring, sterically trapping the tail in a noncovalent interaction we call a lassoedtail.
-amino group of Gly1 and the-carboxyl of Glu8. The tail (Tyr9-Gly21) passes through the ring (Gly1-Glu8), with Phe19 and Tyr20straddling each side of the ring, sterically trapping the tail in a noncovalent interaction we call a lassoedtail.