| Title: | Structural insights into the ligand binding and releasing mechanism of Antheraea polyphemus pheromone-binding protein 1: role of the C-terminal tail |
| Author(s): | Katre UV; Mazumder S; Mohanty S; |
| Address: | "Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA" |
| ISSN/ISBN: | 1520-4995 (Electronic) 0006-2960 (Print) 0006-2960 (Linking) |
| Abstract: | "Pheromone-binding proteins (PBPs) in lepidopteran moths selectively transport the hydrophobic pheromone molecules across the sensillar lymph to trigger the neuronal response. Moth PBPs are known to bind ligand at physiological pH and release it at acidic pH while undergoing a conformational change. Two molecular switches are considered to play a role in this mechanism: (i) protonation of His(70) and His(95) situated at one end of binding pocket and (ii) switch of the unstructured C-terminus at the other end of the binding pocket to a helix that enters the pocket. We have reported previously the role of the histidine-driven switch in ligand release for Antheraea polyphemus PBP1 (ApolPBP1). Here we show that the C-terminus plays a role in the ligand release and binding mechanism of ApolPBP1. The C-terminus truncated mutants of ApolPBP1 (ApolPBP1DeltaP129-V142 and ApolPBP1H70A/H95ADeltaP129-V142) exist only in the bound conformation at all pH levels, and they fail to undergo pH- or ligand-dependent conformational switching. Although these proteins could bind ligands even at acidic pH unlike wild-type ApolPBP1, they had ~4-fold reduced affinity for the ligand at both acidic and physiological pH compared to that of wild-type ApolPBP1 and ApolPBP1H70A/H95A. Thus, apart from helping in ligand release at acidic pH, the C-terminus in ApolPBP1 also plays an important role in ligand binding and/or locking the ligand in the binding pocket. Our results are in stark contrast to those reported for BmorPBP and AtraPBP, where C-terminus truncated proteins had similar or increased pheromone binding affinity at any pH" |
| Keywords: | Animals Carrier Proteins/*chemistry/genetics/metabolism Hydrogen-Ion Concentration Insect Proteins/*chemistry/genetics/metabolism Magnetic Resonance Spectroscopy Molecular Structure Moths Mutation/genetics Pheromones/*metabolism Protein Binding Protein Co; |
| Notes: | "MedlineKatre, Uma V Mazumder, Suman Mohanty, Smita eng R21 DK082397/DK/NIDDK NIH HHS/ DK082397/DK/NIDDK NIH HHS/ Research Support, N.I.H., Extramural Research Support, U.S. Gov't, Non-P.H.S. 2013/01/19 Biochemistry. 2013 Feb 12; 52(6):1037-44. doi: 10.1021/bi301393v. Epub 2013 Jan 31" |
