Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids

Sabrina Gazzarrini, Ming Kang, Alessandra Abenavoli, Giulia Romani, Claudio Olivari, Daniele Gaslini, Giuseppina Ferrara, James L. Van Etten, Michael Kreim, Stefan M. Kast, Gerhard Thiel, Anna Moroni

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)295-303
Number of pages9
JournalBiochemical Journal
Volume420
Issue number2
DOIs
Publication statusPublished - Jun 1 2009

    Fingerprint

Keywords

  • Chlorella virus ATCV-1
  • K/Rb selectivity
  • Kcv
  • Phycodnavirus
  • Viral K channel
  • Yeast complementation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Gazzarrini, S., Kang, M., Abenavoli, A., Romani, G., Olivari, C., Gaslini, D., ... Moroni, A. (2009). Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids. Biochemical Journal, 420(2), 295-303. https://doi.org/10.1042/BJ20090095