Serum amyloid A is a retinol binding protein that transports retinol during bacterial infection

Mehabaw G. Derebe, Clare M. Zlatkov, Sureka Gattu, Kelly A. Ruhn, Shipra Vaishnava, Gretchen E. Diehl, John B. MacMillan, Noelle S. Williams, Lora V. Hooper

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


Retinol plays a vital role in the immune response to infection, yet proteins that mediate retinol transport during infection have not been identified. Serum amyloid A (SAA) proteins are strongly induced in the liver by systemic infection and in the intestine by bacterial colonization, but their exact functions remain unclear. Here we show that mouse and human SAAs are retinol binding proteins. Mouse and human SAAs bound retinol with nanomolar affinity, were associated with retinol in vivo, and limited the bacterial burden in tissues after acute infection. We determined the crystal structure of mouse SAA3 at a resolution of 2 Å, finding that it forms a tetramer with a hydrophobic binding pocket that can accommodate retinol. Our results thus identify SAAs as a family of microbe-inducible retinol binding proteins, reveal a unique protein architecture involved in retinol binding, and suggest how retinol is circulated during infection.

Original languageEnglish (US)
Article numbere03206
Pages (from-to)1-18
Number of pages18
Issue numberJuly2014
StatePublished - Jul 29 2014

ASJC Scopus subject areas

  • Neuroscience(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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