Molecular evolution of a gene cluster of serine proteases expressed in the Anopheles gambiae female reproductive tract

BMC Evolutionary Biology

Allegra Via¹  Domenico Raimondo²  Federica Tammaro³  Francesco Baldini⁴  Phillip George⁵  Emiliano Mancini⁶ 

[1] Department of Entomology, Virginia Tech, Blacksburg, USA;Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Universit di Roma, Rome, Italy;Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Universit di Perugia, Terni, Italy;Dipartimento di Scienze Biochimiche, Sapienza Universit di Roma, Rome, Italy;Division of Cell and Molecular Biology, Imperial College London, London, UK;Istituto-Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Sanit Pubblica e Malattie Infettive, Sapienza Universit di Roma, Rome, Italy

关键词: molecular evolution;    reproduction;    adaptive evolution;    gene duplication;    Anopheles gambiae complex;   

DOI  :  10.1186/1471-2148-11-72

学科分类：生物科学（综合）

来源: BioMed Central

【 摘 要 】

Genes involved in post-mating processes of multiple mating organisms are known to evolve rapidly due to coevolution driven by sexual conflict among male-female interacting proteins. In the malaria mosquito Anopheles gambiae - a monandrous species in which sexual conflict is expected to be absent or minimal - recent data strongly suggest that proteolytic enzymes specifically expressed in the female lower reproductive tissues are involved in the processing of male products transferred to females during mating. In order to better understand the role of selective forces underlying the evolution of proteins involved in post-mating responses, we analysed a cluster of genes encoding for three serine proteases that are down-regulated after mating, two of which specifically expressed in the atrium and one in the spermatheca of A. gambiae females. The analysis of polymorphisms and divergence of these female-expressed proteases in closely related species of the A. gambiae complex revealed a high level of replacement polymorphisms consistent with relaxed evolutionary constraints of duplicated genes, allowing to rapidly fix novel replacements to perform new or more specific functions. Adaptive evolution was detected in several codons of the 3 genes and hints of episodic selection were also found. In addition, the structural modelling of these proteases highlighted some important differences in their substrate specificity, and provided evidence that a number of sites evolving under selective pressures lie relatively close to the catalytic triad and/or on the edge of the specificity pocket, known to be involved in substrate recognition or binding. The observed patterns suggest that these proteases may interact with factors transferred by males during mating (e.g. substrates, inhibitors or pathogens) and that they may have differently evolved in independent A. gambiae lineages. Our results - also examined in light of constraints in the application of selection-inference methods to the closely related species of the A. gambiae complex - reveal an unexpectedly intricate evolutionary scenario. Further experimental analyses are needed to investigate the biological functions of these genes in order to better interpret their molecular evolution and to assess whether they represent possible targets for limiting the fertility of Anopheles mosquitoes in malaria vector control strategies.

【 授权许可】

CC BY