Structural highlights
Function
CBPB1_AEDAE Carboxypeptidase that preferentially hydrolyzes arginine and lysine residues at the C-terminus (PubMed:34750241). During infection by dengue virus, may play a role in preventing viral packaging, maturation, and release from the midgut (PubMed:25521592).[1] [2]
Publication Abstract from PubMed
Metallocarboxypeptidases (MCPs) in the mosquito midgut play crucial roles in infection, as well as in mosquito dietary digestion, reproduction, and development. MCPs are also part of the digestive system of plant-feeding insects, representing key targets for inhibitor development against mosquitoes/mosquito-borne pathogens or as antifeedant molecules against plant-feeding insects. Notably, some non-mosquito insect B-type MCPs are primarily insensitive to plant protease inhibitors (PPIs) such as the potato carboxypeptidase inhibitor (PCI; MW 4 kDa), an inhibitor explored for cancer treatment and insecticide design. Here, we report the crystal structure of Aedes aegypti carboxypeptidase-B1 (CPBAe1)-PCI complex and compared the binding with that of PCI-insensitive CPBs. We show that PCI accommodation is determined by key differences in the active-site regions of MCPs. In particular, the loop regions alpha6-alpha7 (Leu(242) -Ser(250) ) and beta8-alpha8 (Pro(269) -Pro(280) ) of CPBAe1 are replaced by alpha-helices in PCI-insensitive insect Helicoverpa zea CPBHz. These alpha-helices protrude into the active-site pocket of CPBHz, restricting PCI insertion and rendering the enzyme insensitive. We further compared our structure with the only other PCI complex available, bovine CPA1-PCI. The potency of PCI against CPBAe1 (K(i) = 14.7 nM) is marginally less than that of bovine CPA1 (K(i) = 5 nM). Structurally, the above loop regions that accommodate PCI binding in CPBAe1 are similar to that of bovine CPA1, although observed changes in proteases residues that interact with PCI could account for the differences in affinity. Our findings suggest that PCI sensitivity is largely dictated by structural interference, which broadens our understanding of carboxypeptidase inhibition as a mosquito population/parasite control strategy.
Structure of Aedes aegypti carboxypeptidase B1-inhibitor complex uncover the disparity between mosquito and non-mosquito insect carboxypeptidase inhibition mechanism.,Gavor E, Choong YK, Jobichen C, Mok YK, Kini RM, Sivaraman J Protein Sci. 2021 Dec;30(12):2445-2456. doi: 10.1002/pro.4212. Epub 2021 Nov 5. PMID:34658092[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Tham HW, Balasubramaniam VR, Tejo BA, Ahmad H, Hassan SS. CPB1 of Aedes aegypti interacts with DENV2 E protein and regulates intracellular viral accumulation and release from midgut cells. Viruses. 2014 Dec 16;6(12):5028-46. PMID:25521592 doi:10.3390/v6125028
- ↑ Gavor E, Choong YK, Tulsian NK, Nayak D, Idris F, Sivaraman H, Ting DHR, Sylvie A, Mok YK, Kini RM, Sivaraman J. Structure of Aedes aegypti procarboxypeptidase B1 and its binding with Dengue virus for controlling infection. Life Sci Alliance. 2021 Nov 8;5(1):e202101211. PMID:34750241 doi:10.26508/lsa.202101211
- ↑ Gavor E, Choong YK, Jobichen C, Mok YK, Kini RM, Sivaraman J. Structure of Aedes aegypti carboxypeptidase B1-inhibitor complex uncover the disparity between mosquito and non-mosquito insect carboxypeptidase inhibition mechanism. Protein Sci. 2021 Dec;30(12):2445-2456. PMID:34658092 doi:10.1002/pro.4212
