title: Identification of an HV 1 voltage-gated proton channel in insects.
abstract: The voltage-gated proton channel 1 (HV 1) is an important component of the cellular proton extrusion machinery and is essential for charge compensation during the respiratory burst of phagocytes. HV 1 has been identified in a wide range of eukaryotes throughout the animal kingdom, with the exception of insects. Therefore, it has been proposed that insects do not possess an HV 1 channel. In the present study, we report the existence of an HV 1-type proton channel in insects. We searched insect transcriptome shotgun assembly (TSA) sequence databases and found putative HV 1 orthologues in various polyneopteran insects. To confirm that these putative HV 1 orthologues were functional channels, we studied the HV 1 channel of Nicoletia phytophila (NpHV 1), an insect of the Zygentoma order, in more detail. NpHV 1 comprises 239 amino acids and is 33% identical to the human voltage-gated proton channel 1. Patch clamp measurements in a heterologous expression system showed proton selectivity, as well as pH- and voltage-dependent gating. Interestingly, NpHV 1 shows slightly enhanced pH-dependent gating compared to the human channel. Mutations in the first transmembrane segment at position 66 (Asp66), the presumed selectivity filter, lead to a loss of proton-selective conduction, confirming the importance of this aspartate residue in voltage-gated proton channels.
  
  
  METHODS
  Nucleotide sequence data have been deposited in the GenBank database under accession number KT780722.
authors: Institute of Complex Systems, Zelluläre Biophysik (ICS-4) Forschungszentrum Jülich, Germany.
authors: Gustavo
authors: G
authors: Chaves
authors: Zoologisches Institut, Biozentrum Universität zu Köln, Germany.
authors: Christian
authors: C
authors: Derst
authors: Institute of Complex Systems, Zelluläre Biophysik (ICS-4) Forschungszentrum Jülich, Germany.
authors: Arne
authors: A
authors: Franzen
authors: Sugadaira Montane Research Center, University of Tsukuba, Ueda, Japan.
authors: Yuta
authors: Y
authors: Mashimo
authors: Sugadaira Montane Research Center, University of Tsukuba, Ueda, Japan.
authors: Ryuichiro
authors: R
authors: Machida
authors: Institute of Complex Systems, Zelluläre Biophysik (ICS-4) Forschungszentrum Jülich, Germany.|Institut für Physiologie und Pathophysiologie, Paracelsus Universität Salzburg Standort Nürnberg, Nuremberg, Germany.
authors: Boris
authors: B
authors: Musset
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D004594:Electrophysiology; D006801:Humans; D007313:Insecta / Q000145:classification / Q000378:metabolism*; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology*; D008969:Molecular Sequence Data; D011522:Protons; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D007473:Ion Channels; D011522:Protons; D012333:RNA, Messenger
keywords: HVCN1; insect; ion channel; patch clamp; structure-function