Novel Cell Wall Hydrolase CwlC from Bacillus thuringiensis Is Essential for Mother Cell Lysis

Author:

Chen Xiaomin1,Gao Tantan1,Peng Qi1,Zhang Jie1,Chai Yunrong2,Song Fuping1

Affiliation:

1. State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China

2. Department of Biology, Northeastern University, Boston, Massachusetts, USA

Abstract

ABSTRACT In this study, a sporulation-specific gene (tentatively named cwlC ) involved in mother cell lysis in Bacillus thuringiensis was characterized. The encoded CwlC protein consists of an N-terminal N -acetylmuramoyl- l -alanine amidase (Mur N Ac-LAA) domain and a C-terminal amidase02 domain. The recombinant histidine-tagged CwlC proteins purified from Escherichia coli were able to directly bind to and digest the B. thuringiensis cell wall. The CwlC point mutations at the two conserved glutamic acid residues (Glu-24 and Glu-140) shown to be critical for the catalytic activity in homologous amidases resulted in a complete loss of cell wall lytic activity, suggesting that CwlC is an N -acetylmuramoyl- l -alanine amidase. Results of transcriptional analyses indicated that cwlC is transcribed as a monocistronic unit and that its expression is dependent on sporulation sigma factor K (σ K ). Deletion of cwlC completely blocked mother cell lysis during sporulation without impacting the sporulation frequency, Cry1Ac protein production, and insecticidal activity. Taken together, our data suggest that CwlC is an essential cell wall hydrolase for B. thuringiensis mother cell lysis during sporulation. Engineered B. thuringiensis strains targeting cwlC , which allows the crystal inclusion to remain encapsulated in the mother cell at the end of sporulation, may have the potential to become more effective biological control agents in agricultural applications since the crystal inclusion remains encapsulated in the mother cell at the end of sporulation. IMPORTANCE Mother cell lysis has been well studied in Bacillus subtilis , which involves three distinct yet functionally complementary cell wall hydrolases. In this study, a novel cell wall hydrolase, CwlC, was investigated and found to be essential for mother cell lysis in Bacillus thuringiensis . CwlC of B. thuringiensis only shows 9 and 21% sequence identity with known B. subtilis mother cell hydrolases CwlB and CwlC, respectively, suggesting that mechanisms of mother cell lysis may differ between B. subtilis and B. thuringiensis . The cwlC gene deletion completely blocked the release of spores and crystals from the mother cell without affecting insecticidal activity. This may provide a new effective strategy for crystal encapsulation against UV light inactivation.

Funder

The National Key Research and Development Program of China

National Natural Science Foundation of China

Publisher

American Society for Microbiology

Subject

Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3