Evolution of the Heme Peroxidases of Culicidae (Diptera)

Austin L Hughes

doi:10.1155/2012/146387

Abstract

Phylogenetic analysis of heme peroxidases (HPXs) of Culicidae and other insects revealed six highly conserved ancient HPX lineages, each of which originated by gene duplication prior to the most recent common ancestor (MRCA) of Hemimetabola and Holmetabola. In addition, culicid HPX7 and HPX12 arose by gene duplication after the MRCA of Culicidae and Drosophilidae, while HPX2 orthologs were not found in any other order analyzed except Diptera. Within Diptera, HPX2, HPX7, and HPX12 were relatively poorly conserved at the amino acid level in comparison to the six ancient lineages. The genome ofAnopheles gambiaeincluded genes ecoding five proteins (HPX10, HPX11, HPX13, HXP14, and HPX15) without ortholgs in other genomes analyzed. Overall, gene expression patterns did not seem to reflect phylogenetic relationships, but genes that evolved rapidly at the amino acid sequence level tended to have divergent expression patterns as well. The uniquely high level of duplication of HPXs inA. gambiaemay have played a role in coevolution with malaria parasites.

Highlights

The production of nitric oxide (NO) is an important immune defense mechanism against cellular microorganisms in insects and other invertebrates [1]
NOX5 is represented by a single ortholog in insects, but HPX2 is a member of a multigene heme peroxidase family in A. gambiae and other insects [3,4,5]
A phylogenetic tree of insect HPXs was constructed by the maximum likelihood (ML) method using the WAG+G+I model at 301 aligned amino acid sites (Figure 1)

Summary

Introduction

The production of nitric oxide (NO) is an important immune defense mechanism against cellular microorganisms in insects and other invertebrates [1]. Other mosquito heme peroxidases (HPXs) of known function include those expressed in the salivary glands of female A. gambiae and A. albimanus [6, 7] and one involved in the catalysis of protein-crosslinking in the chorion of Aedes aegypti eggs [8]. In another member of Diptera, the fruit fly Drosophila melanogaster, heme peroxidases have been implicated in chorion assembly and other developmental processes [9, 10]

Methods

Results

Conclusion