Jennings C, West J, Waine C, Craik D, Anderson M
Department of Biochemistry, La Trobe University, Bundoora, VIC, 3083, Australia.
Proc Natl Acad Sci U S A. 2001 Sep 11;98(19):10614-9. doi: 10.1073/pnas.191366898. Epub 2001 Sep 4.
Several members of the Rubiaceae and Violaceae families produce a series of cyclotides or macrocyclic peptides of 29-31 amino acids with an embedded cystine knot. We aim to understand the mechanism of synthesis of cyclic peptides in plants and have isolated a cDNA clone that encodes the cyclotide kalata B1 as well as three other clones for related cyclotides from the African plant Oldenlandia affinis. The cDNA clones encode prepropeptides with a 20-aa signal sequence, an N-terminal prosequence of 46-68 amino acids and one, two, or three cyclotide domains separated by regions of about 25 aa. The corresponding cyclotides have been isolated from plant material, indicating that the cyclotide domains are excised and cyclized from all four predicted precursor proteins. The exact processing site is likely to lie on the N-terminal side of the strongly conserved GlyLeuPro or SerLeuPro sequence that flanks both sides of the cyclotide domain. Cyclotides have previously been assigned an antimicrobial function; here we describe a potent inhibitory effect on the growth and development of larvae from the Lepidopteran species Helicoverpa punctigera.
茜草科和堇菜科的几个成员会产生一系列环肽或由29至31个氨基酸组成的大环肽，其具有嵌入的胱氨酸结。我们旨在了解植物中环肽的合成机制，并从非洲植物近缘老鹳草中分离出一个编码环肽kalata B1的cDNA克隆以及其他三个相关环肽的克隆。这些cDNA克隆编码前原肽，其具有20个氨基酸的信号序列、46至68个氨基酸的N端前序列以及由约25个氨基酸的区域隔开的一个、两个或三个环肽结构域。相应的环肽已从植物材料中分离出来，这表明环肽结构域是从所有四种预测的前体蛋白中切除并环化的。确切的加工位点可能位于环肽结构域两侧高度保守的GlyLeuPro或SerLeuPro序列的N端一侧。环肽先前被赋予了抗菌功能；在此我们描述了其对鳞翅目物种棉铃虫幼虫生长发育的强大抑制作用。
