Model-Guided Mutagenesis Drives Functional Studies of Human NHA2, Implicated in Hypertension

Maya Schushan, Minghui Xiang, Pavel Bogomiakov, Etana Padan, Rajini Rao, Nir Ben-Tal

Research output: Contribution to journalArticle

Abstract

Human NHA2 is a poorly characterized Na+/H+ antiporter recently implicated in essential hypertension. We used a range of computational tools and evolutionary conservation analysis to build and validate a three-dimensional model of NHA2 based on the crystal structure of a distantly related bacterial transporter, NhaA. The model guided mutagenic evaluation of transport function, ion selectivity, and pH dependence of NHA2 by phenotype screening in yeast. We describe a cluster of essential, highly conserved titratable residues located in an assembly region made of two discontinuous helices of inverted topology, each interrupted by an extended chain. Whereas in NhaA, oppositely charged residues compensate for partial dipoles generated within this assembly, in NHA2, polar but uncharged residues suffice. Our findings led to a model for transport mechanism that was compared to the well-known electroneutral NHE1 and electrogenic NhaA subtypes. This study establishes NHA2 as a prototype for the poorly understood, yet ubiquitous, CPA2 antiporter family recently recognized in plants and metazoans and illustrates a structure-driven approach to derive functional information on a newly discovered transporter.

Original languageEnglish (US)
Pages (from-to)1181-1196
Number of pages16
JournalJournal of molecular biology
Volume396
Issue number5
DOIs
StatePublished - 2010

Keywords

  • CPA
  • Mechanism
  • Model structure
  • Mutagenesis
  • NHA2

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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