Antimicrobial activity of a honeybee (Apis cerana) venom Kazal-type serine protease inhibitor.
Insect-derived Kazal-type serine protease inhibitors exhibit thrombin, elastase, plasmin, proteinase K, or subtilisin A inhibition activity, but so far, no functional roles for bee-derived Kazal-type serine protease inhibitors have been identified. In this study, a bee (Apis cerana) venom Kazal-type serine protease inhibitor (AcKTSPI) that acts as a microbial serine protease inhibitor was identified. AcKTSPI contained a single Kazal domain that displayed six conserved cysteine residues and a P1 threonine residue. AcKTSPI was expressed in the venom gland and was present as a 10-kDa peptide in bee venom. Recombinant AcKTSPI Kazal domain (AcKTSPI-Kd) expressed in baculovirus-infected insect cells demonstrated inhibitory activity against subtilisin A (Ki 67.03 nM) and proteinase K (Ki 91.53 nM), but not against α-chymotrypsin or trypsin, which implies a role for AcKTSPI as a microbial serine protease inhibitor. However, AcKTSPI-Kd exhibited no detectable inhibitory effects on factor Xa, thrombin, tissue plasminogen activator, or elastase. Additionally, AcKTSPI-Kd bound directly to Bacillus subtilis, Bacillus thuringiensis, Beauveria bassiana, and Fusarium graminearum but not to Escherichia coli. Consistent with these findings, AcKTSPI-Kd showed antibacterial activity against Gram-positive bacteria and antifungal activity against both plant-pathogenic and entomopathogenic fungi. These findings constitute molecular evidence that AcKTSPI acts as an inhibitor of microbial serine proteases. This paper provides a novel view of the antimicrobial functions of a bee venom Kazal-type serine protease inhibitor.
College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea.
Bo Yeon
BY
Kim
Kwang Sik
KS
Lee
Feng Ming
FM
Zou
Hu
H
Wan
Yong Soo
YS
Choi
Hyung Joo
HJ
Yoon
Hyung Wook
HW
Kwon
Yeon Ho
YH
Je
Byung Rae
BR
Jin
D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001514:Bee Venoms / Q000737:chemistry*; D001516:Bees / Q000201:enzymology*; D015152:Blotting, Northern; D003001:Cloning, Molecular; D019476:Insect Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
D000890:Anti-Infective Agents; D001514:Bee Venoms; D019476:Insect Proteins; D015842:Serine Proteinase Inhibitors
Antimicrobial activity; Apis cerana; Honeybee; Kazal-type serine protease inhibitor; Microbial serine protease inhibitor; Venom