title: The Signaling Pathway of Caenorhabditis elegans Mediates Chemotaxis Response to the Attractant 2-Heptanone in a Trojan Horse-like Pathogenesis.
abstract: The nematode Caenorhabditis elegans exhibits behavioral responses to a wide range of odorants associated with food and pathogens. A previous study described a Trojan Horse-like strategy of pathogenesis whereby the bacterium Bacillus nematocida B16 emits the volatile organic compound 2-heptanone to trap C. elegans for successful infection. Here, we further explored the receptor for 2-heptanone as well as the pathway involved in signal transduction in C. elegans Our experiments showed that 2-heptanone sensing depended on the function of AWC neurons and a GPCR encoded by str-2 Consistent with the above observation, the HEK293 cells expressing STR-2 on their surfaces showed a transient elevation in intracellular Ca2+levels after 2-heptanone applications. After combining the assays of RNA interference and gene mutants, we also identified the Gα subunits and their downstream components in the olfactory signal cascade that are necessary for responding to 2-heptanone, including Gα subunits of egl-30 and gpa-3, phospholipase C of plc-1and egl-8, and the calcium channel of cmk-1 and cal-1. Our work demonstrates for the first time that an integrated signaling pathway for 2-heptanone response in C. elegans involves recognition by GPCR STR-2, activation by Gα subunits of egl-30/gpa-3 and transfer to the PLC pathway, indicating that a potentially novel olfactory pathway exists in AWC neurons. Meanwhile, since 2-heptanone, a metabolite from the pathogenic bacterium B. nematocida B16, can be sensed by C. elegans and thus strongly attract its host, our current work also suggested coevolution between the pathogenic microorganism and the chemosensory system in C. elegans.
authors.affiliation: From the State Key Lab for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan 650091, China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Neurosurgery of the Second Hospital affiliated with Kunming Medical University, Kunming 650101, China, and.
authors.forename: Ninghui
authors.initials: N
authors.lastname: Zhao
authors.affiliation: From the State Key Lab for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan 650091, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Chen
authors.affiliation: From the State Key Lab for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan 650091, China.
authors.forename: Donghua
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Center Laboratory of the Second Hospital affiliated with Kunming Medical University, Kunming 650101, China.
authors.forename: Jinyuan
authors.initials: J
authors.lastname: Yan
authors.affiliation: From the State Key Lab for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan 650091, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zou
authors.affiliation: From the State Key Lab for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan 650091, China.
authors.forename: Keqin
authors.initials: K
authors.lastname: Zhang
authors.affiliation: From the State Key Lab for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, Yunnan 650091, China, xwhuang@ynu.edu.cn.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Huang
mesh_terms: D000818:Animals; D001407:Bacillus / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000382:microbiology* / Q000502:physiology*; D002633:Chemotaxis; D057809:HEK293 Cells; D006801:Humans; D007659:Ketones / Q000378:metabolism*; D009833:Olfactory Pathways / Q000382:microbiology / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D018035:Receptors, Odorant / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D007659:Ketones; D043562:Receptors, G-Protein-Coupled; D018035:Receptors, Odorant; C514941:Str-2 protein, C elegans; C011917:2-heptanone
keywords: 2-heptanone; Caenorhabditis elegans (C. elegans); G protein-coupled receptor (GPCR); bacterial pathogenesis; chemotaxis; chemotaxis response; co-evolution; microbial pathogens; olfactory pathway; signal transduction