PRIMARY STRUCTURE OF MICROCIN, J25, A BACTERIALLY EXPRESSED ANTIBIOTIC

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 Microcin J25(MccJ25)是一种由21个氨基酸组成的多肽抑制剂，对革兰氏阴性菌依赖DNA的RNA聚合酶具有抑制作用。此前，MccJ25的结构被报道为头尾相连的环，Cyclo(-G(1)GAGHVPEYF(10)VGIGTPISFY(20)G-)。在生化研究、质谱学和核磁共振的基础上，我们证明这种结构是不正确的，并且该肽具有不寻常的结构折叠。MccJ25在Gly1的α-氨基和Glu8的伽马-羧基之间含有内酰胺键。尾巴(Tyr9-Gly21)穿过环(Gly1-Glu8)，Phe19和Tyr20横跨环的两侧，以空间上的相互作用捕获尾巴，我们称之为套索尾巴。这项研究发表在《化学学报》上。2003年10月15日；125(41)：12475-83，并被《化学与工程新闻》报道为2003年的化学亮点之一(《化学与工程新闻》2003年12月22日)。接下来，我们将尝试确定酶的高分辨率X射线结构，这些酶被认为是将前蛋白转化为活性抑制物的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Microcin J25 (MccJ25) is a 21-amino acid peptide inhibitor active against the DNA-dependent RNA polymerase of Gram negative bacteria. Previously, the structure of MccJ25 was reported to be a head-to-tail circle, cyclo(-G(1)GAGHVPEYF(10)VGIGTPISFY(20)G-). On the basis of biochemical studies, mass spectrometry, and NMR, we show that this structure is incorrect, and that the peptide has an extraordinary structural fold. MccJ25 contains an internal lactam linkage between the alpha-amino group of Gly1 and the gamma-carboxyl of Glu8. The tail (Tyr9-Gly21) passes through the ring (Gly1-Glu8), with Phe19 and Tyr20 straddling each side of the ring, sterically trapping the tail in a noncovalent interaction we call a lassoed tail. This work was published in J Am Chem Soc. 2003 Oct 15;125(41):12475-83 and was reported in Chemical and engineering news as one of the chemistry highlights of 2003 (Chem and Eng News Dec 22, 2003). Next, we will attempt to determine the high resolution X-ray structures of the enzymes that are thought to convert the preprotein into the active inhibitor.