title: The standalone aminopeptidase PepN catalyzes the maturation of blasticidin S from leucylblasticidin S.
abstract: The peptidyl nucleoside blasticidin S (BS) isolated from Streptomyces griseochromogenes was the first non-mercurial fungicide used on a large scale to prevent rice blast. In the biosynthesis of BS, leucylblasticidin S (LBS) was suggested as the penultimate metabolite with 20-fold less inhibitory activity than the final product BS. Incomplete conversion of LBS to BS at a variable efficiency ranging from 10% to 90% was observed either in the native strain S. griseochromogenes or a heterologous producer Streptomyces lividans WJ2. In this study, we determined that maturation of BS from LBS is not a spontaneous process but is governed by a standalone peptidase PepN, which hydrolyzes LBS in a pH-sensitive way with most appropriate of pH 7~8 but is inactive when the pH is below 5 or above 10. PepN1 and PepN2, two neighboring PepN homologs from Streptomyces lividans were purified in E. coli but displayed ca.100-fold difference in LBS hydrolytic activity. Overexpression of pepN1 in WJ2 enhanced BS yield by 100% and lowered the ratio of LBS to BS from 2:1 to 2:3. This work presents the expansion of the biological role for PepN in antibiotic maturation and the first report of hydrolysis of beta amide linkage by this conserved enzyme.
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China).
authors.forename: Guiyang
authors.initials: G
authors.lastname: Yu
authors.affiliation: Engineering Research Center of Industrial Microbiology (Ministry of Education), and College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108 (China).
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China).
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China).
authors.forename: Guang
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China).
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331-3507 (USA).
authors.forename: Mark T
authors.initials: MT
authors.lastname: Zabriskie
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China).
authors.forename: Ming
authors.initials: M
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China).
authors.forename: Xinyi
authors.initials: X
authors.lastname: He
mesh_terms: D000626:Aminopeptidases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002384:Catalysis; D009705:Nucleosides / Q000737:chemistry / Q000378:metabolism; D048170:Streptomyces lividans / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D009705:Nucleosides; C075633:pepN protein, Bacteria; C004500:blasticidin S; D000626:Aminopeptidases