Selective transport by SecA2: an expanding family of customized motor proteins

Biochim Biophys Acta. 2014 Aug;1843(8):1674-86. doi: 10.1016/j.bbamcr.2013.10.019. Epub 2013 Oct 31.


The SecA2 proteins are a special class of transport-associated ATPases that are related to the SecA component of the general Sec system, and are found in an increasingly large number of Gram-positive bacterial species. The SecA2 substrates are typically linked to the cell wall, but may be lipid-linked, peptidoglycan-linked, or non-covalently associated S-layer proteins. These substrates can have a significant impact on virulence of pathogenic organisms, but may also aid colonization by commensals. The SecA2 orthologues range from being highly similar to their SecA paralogues, to being distinctly different in apparent structure and function. Two broad classes of SecA2 are evident. One transports multiple substrates, and may interact with the general Sec system, or with an as yet unidentified transmembrane channel. The second type transports a single substrate, and is a component of the accessory Sec system, which includes the SecY paralogue SecY2 along with the accessory Sec proteins Asp1-3. Recent studies indicate that the latter three proteins may have a unique role in coordinating post-translational modification of the substrate with transport by SecA2. Comparative functional and phylogenetic analyses suggest that each SecA2 may be uniquely adapted for a specific type of substrate. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.

Keywords: Accessory Sec system; Asp1; Asp2; Bacterial glycoprotein; Glycoprotein transport; S-layer.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Adenosine Triphosphatases / chemistry*
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Cell Wall / chemistry
  • Cell Wall / metabolism*
  • Gram-Positive Bacteria / chemistry
  • Gram-Positive Bacteria / genetics
  • Membrane Glycoproteins / chemistry*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Membrane Transport Proteins / chemistry*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Molecular Motor Proteins / chemistry
  • Molecular Motor Proteins / metabolism
  • Phylogeny
  • Protein Transport / genetics*
  • SEC Translocation Channels
  • SecA Proteins


  • Bacterial Proteins
  • Membrane Glycoproteins
  • Membrane Transport Proteins
  • Molecular Motor Proteins
  • S-layer proteins
  • SEC Translocation Channels
  • Adenosine Triphosphatases
  • SecA Proteins