3BT4

Crystal Structure Analysis of AmFPI-1, fungal protease inhibitor from Antheraea mylitta

Summary for 3BT4

• Entry DOI: 10.2210/pdb3bt4/pdb
• Descriptor: Fungal protease inhibitor-1, GLYCEROL (3 entities in total)
• Functional Keywords: protease inhibitor, silkworm, serine protease inhibitor, hydrolase inhibitor
• Biological source: Antheraea mylitta (Tasar silkworm)
• Total number of polymer chains: 1
• Total formula weight: 9386.93

Authors

Roy, S.,Aravind, P.,Madhurantakam, C.,Ghosh, A.K.,Sankarananarayanan, R.,Das, A.K. (deposition date: 2007-12-27, release date: 2008-12-30, Last modification date: 2024-10-30)

Primary citation

Roy, S.,Aravind, P.,Madhurantakam, C.,Ghosh, A.K.,Sankaranarayanan, R.,Das, A.K.
Crystal structure of a fungal protease inhibitor from Antheraea mylitta
J.Struct.Biol., 166:79-87, 2009

PubMed Abstract: Indian tasar silk is produced by a wild insect called Antheraea mylitta. Insects do not have any antigen-antibody mediated immune system like vertebrates but they produce a wide variety of effector proteins and peptides possessing potent antifungal and antibacterial activity to combat microbial attack. Antheraea mylitta expresses a fungal protease inhibitor AmFPI-1, in the hemolymph that inhibits alkaline protease of Aspergillus oryzae for protection against fungal infection. AmFPI-1 is purified from the hemolymph, crystallized and the structure is solved using the single isomorphous replacement with anomalous scattering (SIRAS) method to a resolution of 2.1 A. AmFPI-1 is a single domain protein possessing a unique fold that consists of three helices and five beta strands stabilized by a network of six disulfide bonds. The reactive site of AmFPI-1 is located in the loop formed by residues 46-66, wherein Lys54 is the P(1) residue. Superimposition of the loop with reactive sites of other canonical protease inhibitors shows that reactive site conformation of AmFPI-1 is similar to them. The structure of AmFPI-1 provides a framework for the docking of a 1:1 complex between AmFPI-1 and alkaline protease. This study addresses the structural basis of AmFPI-1's specificity towards a fungal serine protease but not to mammalian trypsin and may help in designing specific inhibitors against fungal proteases.

PubMed: 19263521

Experimental method

X-RAY DIFFRACTION (2.1 Å)