title: Activity Augmentation of Amphioxus Peptidoglycan Recognition Protein BbtPGRP3 via Fusion with a Chitin Binding Domain.
abstract: Peptidoglycan recognition proteins (PGRPs), which have been identified in most animals, are pattern recognition molecules that involve antimicrobial defense. Resulting from extraordinary expansion of innate immune genes, the amphioxus encodes many PGRPs of diverse functions. For instance, three isoforms of PGRP encoded by Branchiostoma belcheri tsingtauense, termed BbtPGRP1~3, are fused with a chitin binding domain (CBD) at the N-terminus. Here we report the 2.7 Å crystal structure of BbtPGRP3, revealing an overall structure of an N-terminal hevein-like CBD followed by a catalytic PGRP domain. Activity assays combined with site-directed mutagenesis indicated that the individual PGRP domain exhibits amidase activity towards both DAP-type and Lys-type peptidoglycans (PGNs), the former of which is favored. The N-terminal CBD not only has the chitin-binding activity, but also enables BbtPGRP3 to gain a five-fold increase of amidase activity towards the Lys-type PGNs, leading to a significantly broadened substrate spectrum. Together, we propose that modular evolution via domain shuffling combined with gene horizontal transfer makes BbtPGRP1~3 novel PGRPs of augmented catalytic activity and broad recognition spectrum.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Wang
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Cheng
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Yu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Li
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Dong-Dong
authors.initials: DD
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: Shengfeng
authors.initials: S
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: Anlong
authors.initials: A
authors.lastname: Xu
authors.affiliation: University of Maryland Institute for Bioscience and Biotechnology Research, W. M. Keck Laboratory for Structural Biology, Rockville, Maryland, United States of America; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America.
authors.forename: Roy A
authors.initials: RA
authors.lastname: Mariuzza
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and the Innovation Center for Cell Signaling Network, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
authors.forename: Cong-Zhao
authors.initials: CZ
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002686:Chitin / Q000378:metabolism*; D019143:Evolution, Molecular; D064175:Lancelets; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D011993:Recombinant Fusion Proteins; C118897:peptidoglycan recognition protein; D002686:Chitin