title: L-Glutamate secretion by the N-terminal domain of the Corynebacterium glutamicum NCgl1221 mechanosensitive channel.
abstract: The Corynebacterium glutamicum NCgl1221 mechanosensitive channel mediates L-glutamate secretion by sensing changes in membrane tension caused by treatments such as biotin limitation and penicillin. The NCgl1221 protein has an N-terminal domain (1-286 a.a.) homologous to the Escherichia coli MscS and a long C-terminal domain (287-533 a.a.) of unknown function. In order to investigate the role of the C-terminal domain in L-glutamate secretion, we constructed a series of C-terminally truncated mutants of NCgl1221. We found that the N-terminal domain, homologous to E. coli MscS, retained the ability to cause L-glutamate secretion in response to the treatment. Electrophysiological analysis confirmed that the N-terminal domain mediated L-glutamate secretion. 3D homology modeling has suggested that the N-terminal domain of NCgl1221 has an extra loop structure (221-232 a.a.) that is not found in most other MscS proteins. The mutant NCgl1221, deleted for this loop structure, lost the ability to secrete L-glutamate. In addition, we found that mutant NCgl1221 lacking the C-terminal extracytoplasmic domain (420-533 a.a.) produced L-glutamate without any inducing treatment. These results suggest that the N-terminal domain is necessary and sufficient for the excretion of L-glutamate in response to inducing treatment, and that the C-terminal extracytoplasmic domain has a negative regulatory role in L-glutamate production.
authors: Department of Bioengineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Japan.
authors: Chikako
authors: C
authors: Yamashita
authors: Ken-Ichi
authors: K
authors: Hashimoto
authors: Kosuke
authors: K
authors: Kumagai
authors: Tomoya
authors: T
authors: Maeda
authors: Ayako
authors: A
authors: Takada
authors: Isamu
authors: I
authors: Yabe
authors: Hisashi
authors: H
authors: Kawasaki
authors: Masaaki
authors: M
authors: Wachi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001710:Biotin / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D018698:Glutamic Acid; D001710:Biotin