Identification of the Aedes aegypti peritrophic matrix protein AeIMUCI as a heme-binding protein

Martin Davenport, Patricia H. Alvarenga, Li Shao, Hisashi Fujioka, M. Lucia Bianconi, Pedro L. Oliveira, Marcelo Jacobs-Lorena

Research output: Contribution to journalArticle

Abstract

The gene Aedes aegypti intestinal mucin 1 (AeIMUC1) encodes a putative peritrophic matrix (PM) protein that is expressed in the midgut of mosquito larvae and adults and is upregulated in response to exposure to heavy metals. The AeMUC1 protein has a predicted secretory signal peptide and three putative chitin-binding domains (CBDs) with an intervening mucin-like domain. Immunofluorescence and immunoelectron microscopy experiments established that AeIMUC1 is a bona fide PM protein, and binding of the recombinant protein to chitin was demonstrated in vitro. Previous experiments suggested that the Ae. aegypti PM can bind toxic heme molecules generated during blood digestion. However, the identity of the binding molecule(s) was unknown. Using of heme-agarose beads and spectrophotometric and microcalorimetric titrations, we show that recombinant AeIMUC1 can bind large amounts of heme in vitro, suggesting for the first time a role for a PM protein in heme detoxification during blood digestion. Binding of heme to AeIMUC1 was accompanied by an altered circular dichroism spectrum indicating a change in protein conformation, consistent with an increase in secondary structure. Heme-binding activity was mapped to the AeIMUC1 CBDs, suggesting that these domains possess dual chitin- and heme-binding activity.

Original languageEnglish (US)
Pages (from-to)9540-9549
Number of pages10
JournalBiochemistry
Volume45
Issue number31
DOIs
StatePublished - Aug 8 2006

    Fingerprint

ASJC Scopus subject areas

  • Biochemistry

Cite this

Davenport, M., Alvarenga, P. H., Shao, L., Fujioka, H., Bianconi, M. L., Oliveira, P. L., & Jacobs-Lorena, M. (2006). Identification of the Aedes aegypti peritrophic matrix protein AeIMUCI as a heme-binding protein. Biochemistry, 45(31), 9540-9549. https://doi.org/10.1021/bi0605991