title: A superfamily of voltage-gated sodium channels in bacteria.
abstract: NaChBac, a six-alpha-helical transmembrane-spanning protein cloned from Bacillus halodurans, is the first functionally characterized bacterial voltage-gated Na(+)-selective channel. As a highly expressing ion channel protein, NaChBac is an ideal candidate for high resolution structural determination and structure-function studies. The biological role of NaChBac, however, is still unknown. In this report, another 11 structurally related bacterial proteins are described. Two of these functionally expressed as voltage-dependent Na(+) channels (Na(V)PZ from Paracoccus zeaxanthinifaciens and Na(V)SP from Silicibacter pomeroyi). Na(V)PZ and Na(V)SP share approximately 40% amino acid sequence identity with NaChBac. When expressed in mammalian cell lines, both Na(V)PZ and Na(V)SP were Na(+)-selective and voltage-dependent. However, their kinetics and voltage dependence differ significantly. These single six-alpha-helical transmembrane-spanning subunits constitute a widely distributed superfamily (Na(V)Bac) of channels in bacteria, implying a fundamental prokaryotic function. The degree of sequence homology (22-54%) is optimal for future comparisons of Na(V)Bac structure and function of similarity and dissimilarity among Na(V)Bac proteins. Thus, the Na(V)Bac superfamily is fertile ground for crystallographic, electrophysiological, and microbiological studies.
authors.affiliation: Howard Hughes Medical Institute, Department of Cardiovascular Research, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Koishi
authors.forename: Haoxing
authors.initials: H
authors.lastname: Xu
authors.forename: Dejian
authors.initials: D
authors.lastname: Ren
authors.forename: Betsy
authors.initials: B
authors.lastname: Navarro
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Spiller
authors.forename: Qing
authors.initials: Q
authors.lastname: Shi
authors.forename: David E
authors.initials: DE
authors.lastname: Clapham
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000502:physiology*; D001426:Bacterial Proteins / Q000032:analysis / Q000302:isolation & purification / Q000502:physiology*; D003001:Cloning, Molecular; D004594:Electrophysiology; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017421:Sequence Analysis; D015222:Sodium Channels / Q000032:analysis / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D015222:Sodium Channels