title: Identification of a novel class B scavenger receptor homologue in Portunus trituberculatus: Molecular cloning and microbial ligand binding.
abstract: Class B scavenger receptors (SRBs), which are present in mammals and insects, have been implicated in a wide range of functions. Herein, a novel SRB homologue, PtSRB, was cloned from the swimming crab, Portunus trituberculatus. PtSRB has 538 amino acid residues, and it consists of two transmembrane regions, a large extracellular loop, and two intracellular tails. A phylogenetic analysis showed that PtSRB distinctly clustered with Marsupenaeus japonicas SRB-1 and most Drosophila SRB homologues, including Croquemort, Peste, NinaD, and Santa Maria, but was separate from the Drosophila sensory neuron membrane protein, MjSRB-2, and all vertebrate SRBs. Real-time quantitative PCR analyses showed that the PtSRB gene was constitutively expressed in all tissues tested. When PtSRB was overexpressed in human embryonic kidney 293T cells, it was distributed in the membrane and cytoplasm. Moreover, in vitro assays showed that rPtSRB bound microbial lipopolysaccharide with low affinity, and lipoteichoic acid and peptidoglycan with high affinity. PtSRB transcripts were down-regulated after challenge with Vibrio alginolyticus or white spot syndrome virus, but not after a Candida lusitaniae challenge. This study provides valuable data for understanding the role of SRBs in the host defense against microbial pathogens, which will facilitate future studies of host-pathogen interactions in crabs.
authors.affiliation: Key Laboratory of the Ministry of Education for Applied Marine Biotechnology, School of Marine Science, Ningbo University, Ningbo 315211, China; Marine Science and Engineering College, Qingdao Agricultural University, Qingdao 266109, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.affiliation: Key Laboratory of the Ministry of Education for Applied Marine Biotechnology, School of Marine Science, Ningbo University, Ningbo 315211, China.
authors.forename: Dan-Feng
authors.initials: DF
authors.lastname: Zhang
authors.affiliation: Key Laboratory of the Ministry of Education for Applied Marine Biotechnology, School of Marine Science, Ningbo University, Ningbo 315211, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tao
authors.affiliation: Key Laboratory of the Ministry of Education for Applied Marine Biotechnology, School of Marine Science, Ningbo University, Ningbo 315211, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of the Ministry of Education for Applied Marine Biotechnology, School of Marine Science, Ningbo University, Ningbo 315211, China. Electronic address: zhousuming@nbu.edu.cn.
authors.forename: Su-Ming
authors.initials: SM
authors.lastname: Zhou
authors.affiliation: Key Laboratory of the Ministry of Education for Applied Marine Biotechnology, School of Marine Science, Ningbo University, Ningbo 315211, China. Electronic address: wangguoliang@nbu.edu.cn.
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003386:Brachyura / Q000145:classification / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D008024:Ligands; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051122:Scavenger Receptors, Class B / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D044149:Vibrio alginolyticus / Q000502:physiology; D046848:White spot syndrome virus 1 / Q000502:physiology
chemical_list: D060829:Arthropod Proteins; D018076:DNA, Complementary; D008024:Ligands; D012333:RNA, Messenger; D051122:Scavenger Receptors, Class B
keywords: Cellular localization; Class B scavenger receptor; Expression analysis; Microbial ligands; Portunus trituberculatus