Chlorella virus PBCV-1 (Paramecium bursaria chlorella virus-1) encodes the smallest protein (94 amino acids, named Kcv) previously known to form a functionalK+ channel in heterologous systems. In this paper, we characterize another chlorella virus encoded K+ channel protein (82 amino acids, named ATCV-1 Kcv) that forms a functional channel in Xenopus oocytes and rescues Saccharomyces cerevisiae mutants that lack endogenous K+ uptake systems. Compared with the larger PBCV-1 Kcv, ATCV-1 Kcv lacks a cytoplasmic N-terminus and has a reduced number of charged amino acids in its turret domain. Despite these deficiencies, ATCV-1 Kcv accomplishes all the major features of K+ channels: it assembles into a tetramer, is K+ selective and is inhibited by the canonical K+ channel blockers, barium and caesium. Single channel analyses reveal a stochastic gating behaviour and a voltage-dependent conductance that resembles the macroscopic I/V relationship. One difference between PBCV-1 and ATCV-1 Kcv is that the latter is more permeable to K+ than Rb+. This difference is partially explained by the presence of a tyrosine residue in the selective filter of ATCV-1 Kcv, whereas PBCV-1 Kcv has a phenylalanine. Hence, ATCV-1 Kcv is the smallest protein to form a K+ channel and it will serve as a model for studying structure-function correlations inside the potassium channel pore.
Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids / S. Gazzarrini, M. Kang, A. Abenavoli, G. Romani, C. Olivari, D. Gaslini, G. Ferrara, J.L. Van Etten, M. Kreim, S.M. Kast, G. Thiel, A. Moroni. - In: BIOCHEMICAL JOURNAL. - ISSN 0264-6021. - 420:2(2009), pp. 295-303.
|Titolo:||Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids|
GAZZARRINI, SABRINA (Primo)
MORONI, ANNA (Ultimo)
|Parole Chiave:||chlorella virus ATCV-1 ; Kcv ; K+/Rb+ selectivity ; phycodnavirus ; viral K+ channel ; yeast complementation|
|Settore Scientifico Disciplinare:||Settore BIO/04 - Fisiologia Vegetale|
|Data di pubblicazione:||2009|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1042/BJ20090095|
|Appare nelle tipologie:||01 - Articolo su periodico|