Two Kazal-type protease inhibitors from Macrobrachium nipponense and Eriocheir sinensis: comparative analysis of structure and activities |
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Authors: | Qian Ye-Qing Li Ye Yang Fan Yu Yan-Qin Yang Jin-Shu Yang Wei-Jun |
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Institution: | a Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, PR China b Key Laboratory of Applied Technology of Marine Biology, Ministry of Education, Faculty of Life Science and Biotechnology, Ningbo University, Ningbo, Zhejiang 315211, PR China |
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Abstract: | Kazal-type inhibitors (KPIs) play important roles in many biological and physiological processes, such as blood clotting, the immune response and reproduction. In the present study, two male reproductive tract KPIs, termed Man-KPI and Ers-KPI, were identified in Macrobrachium nipponense and Eriocheir sinensis, respectively. The inhibitory activities of recombinant Man-KPI and Ers-KPI against chymotrypsin, elastase, trypsin and thrombin were determined. The results showed that both of them strongly inhibit chymotrypsin and elastase. Kinetic studies were performed to elucidate their inhibition mechanism. Furthermore, individual domains were also expressed to learn further which domain contributes to the inhibitory activities of intact KPIs. Only Man-KPI_domain3 is active in the inhibition of chymotrypsin and elastase. Meanwhile, Ers-KPI_domain2 and 3 are responsible for inhibition of chymotrypsin, and Ers-KPI_domains2, 3 and 4 are responsible for the inhibition of elastase. Meanwhile, the inhibitory activities of these two KPIs toward Macrobrachium rosenbergii, M. nipponense and E. sinensis sperm were compared with that of the Kazal-type peptidase inhibitor (MRPINK) characterized from the M. rosenbergii reproductive tract in a previous study. The results demonstrated that KPIs can completely inhibit the gelatinolytic activities of sperm proteases from their own species, while different levels of cross-inhibition were observed between KPI and proteases from different species. These results may provide new perspective to further clarify the mechanism of KPI-proteases interaction in the male reproductive system. |
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Keywords: | Kazal-type protease inhibitor Male reproductive tract Domain Macrobrachium nipponense Eriocheir sinensis |
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