B11E-0479
Structural and Molecular Basis for the Novel Catalytic Mechanism and Evolution of DddP, an Abundant Peptidase-Like Bacterial Dimethylsulfoniopropionate Lyase: A New Enzyme from an Old Fold
Monday, 14 December 2015
Poster Hall (Moscone South)
Yu-Zhong Zhang1, Peng Wang1, Xiu-Lan Chen1, Chun-Yang Li1, Xiang Gao1, Deyu Zhu1, Bin-Bin Xie1, Qi-Long Qin1, Xi-Ying Zhang1, Hai-Nan Su1, Bai-Cheng Zhou2 and Luying Xun3, (1)Shandong University, State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Jinan, China, (2)Shandong University, Marine Biotechnology Research Center, Jinan, China, (3)Shandong University, State Key Laboratory of Microbial Technology, Jinan, China
Abstract:
The microbial cleavage of dimethylsulfoniopropionate (DMSP) generates volatile dimethyl sulfide (DMS) and is an important step in global sulfur and carbon cycles. DddP is a DMSP lyase in marine bacteria and the deduced dddP gene product is abundant in marine metagenomic data sets. However, DddP belongs to the M24 peptidase family according to sequence alignment. Peptidases hydrolyze C-N bonds but DddP is deduced to cleave C-S bonds. Mechanisms responsible for this striking functional shift are currently unknown. We determined the structures of DMSP lyase RlDddP (the DddP from Ruegeria lacuscaerulensis ITI_1157) bound to inhibitory 2-(N-morpholino) ethanesulfonic acid or PO43- and of two mutants of RlDddP bound to acrylate. Based on structural, mutational and biochemical analyses, we characterized a new ion-shift catalytic mechanism of RlDddP for DMSP cleavage. Further, we suggested the structural mechanism leading to the loss of peptidase activity and the subsequent development of DMSP lyase activity in DddP. This study sheds light on the catalytic mechanism and the divergent evolution of DddP, leading to a better understanding of marine bacterial DMSP catabolism and global DMS production.
