A glycine- and glutamate-rich protein is female salivary gland-specific and abundant in the malaria vector Anopheles dirus B (Diptera: Culicidae).
Before transmission, malaria parasites reside in the salivary glands of their female mosquito hosts. Saliva proteins assist in blood feeding and also may influence the ability of mosquitoes to transmit malaria. We attempted to identify and isolate cDNAs encoding proteins expressed at a high level in the salivary glands of a malaria vector, Anopheles dirus B Peyton and Harrison (= An. cracens) (Diptera: Culicidae). A major protein with an estimated molecular mass of 35 kDa and an isoelectric point (pI) of approximately 4 was detected on a two-dimensional (2D) gel. Internal peptide sequences of the protein spot showed high similarity to sequences present in the conserved C-terminal domain of glycine- and glutamate (GE)-rich proteins. A full-length cDNA encoding this protein was isolated from a salivary gland cDNA library of female An. dirus B. The cDNA encoded a 256-residue protein with a calculated molecular mass of 25.4 kDa and a pI of 3.9. BLAST analysis confirmed that it is a member of the GE-rich family. Compositional and sequence analysis of this and other family members revealed a highly acidic N-terminal region of variable length and low sequence conservation and a well conserved C-terminal domain containing 10 identical residues across the 13 known members of the gene family in mosquitoes. The An. dirus B GE-rich transcript was detected by reverse transcription-polymerase chain reaction (PCR) only in the female salivary glands, indicating that this protein is female saliva-specific. The GE-rich proteins may function as a salivary lubricant to facilitate blood feeding.
Jariyapan
Narissara
N
Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand. narsuwan@mail.med.cmu.ac.th
Choochote
Wej
W
Jitpakdi
Atchariya
A
Harnnoi
Thasaneeya
T
Siriyasatein
Padet
P
Wilkinson
Mark C
MC
Bates
Paul A
PA
D000595:Amino Acid Sequence; D000818:Animals; D000852:Anopheles / Q000502:physiology*; D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000737:chemistry; D005260:Female; D018698:Glutamic Acid / Q000032:analysis; D005998:Glycine / Q000032:analysis; D019476:Insect Proteins / Q000096:biosynthesis / Q000737:chemistry*; D007303:Insect Vectors / Q000502:physiology*; D008288:Malaria / Q000517:prevention & control / Q000635:transmission; D008297:Male; D008969:Molecular Sequence Data; D012269:Ribosomal Proteins / Q000032:analysis; D012471:Salivary Proteins and Peptides / Q000096:biosynthesis / Q000737:chemistry*; D016415:Sequence Alignment
D017931:DNA Primers; D018076:DNA, Complementary; D019476:Insect Proteins; D012269:Ribosomal Proteins; D012471:Salivary Proteins and Peptides; D018698:Glutamic Acid; C016700:ribosomal protein L7-L12; D005998:Glycine