title: A C-terminal truncated mutation of licC attenuates the virulence of Streptococcus pneumoniae.
abstract: LicC has been identified as a virulence factor of Streptococcus pneumoniae. However, its role in virulence is still not fully understood because deletion of licC is lethal for the bacterium. In this study, a mutant with 78-bp truncation at the C-terminus of licC was obtained from a signature-tagged mutagenesis (STM) library. The mutant was viable with a large reduction in enzymatic activity as CTP:phosphocholine cytidylyltransferase detected in vitro using a firefly luciferase assay. The mutation attenuated the adhesion and invasion of S. pneumoniae ST556 (serotype 19F) to epithelial cells by 72% and 80%, respectively, and increased the phagocytosis by macrophages for 16.5%, compared to the parental strain. When the mutation was introduced into the encapsulated D39 strain (serotype 2), it led to attenuated virulence in mouse models either by intranasal colonization or by intraperitoneal infection. In addition, the phosphocholine (PCho) on cell surface was decreased, and the choline binding proteins (CBPs) were impaired, which may explain the attenuated virulence of the mutant. These observations indicate that C-terminus of licC is accounted for the main activity of LicC in PCho metabolism and is essential for the virulence of S. pneumoniae, which provides a novel target for drug design against pneumococcal infection.
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: mumufly@126.com.
authors.forename: Xian-Fei
authors.initials: XF
authors.lastname: Zeng
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: cmbmayy@fmmu.edu.cn.
authors.forename: Yueyun
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: zhangzh@fmmu.edu.cn.
authors.forename: Liu
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: iamwolf-snzq@163.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: xy850510@126.com.
authors.forename: Yijuan
authors.initials: Y
authors.lastname: Xin
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: clliangliang311@163.com.
authors.forename: Liang
authors.initials: L
authors.lastname: Chang
authors.affiliation: Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing 100017, China. Electronic address: zhangjr@biomed.tsinghua.edu.cn.
authors.forename: Jing-Ren
authors.initials: JR
authors.lastname: Zhang
authors.affiliation: Department of Clinical Laboratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: haoxkg@fmmu.edu.cn.
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Hao
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002460:Cell Line; D019916:Choline-Phosphate Cytidylyltransferase / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000382:microbiology; D005798:Genes, Bacterial; D020043:Genes, Essential; D006801:Humans; D008264:Macrophages / Q000276:immunology; D051379:Mice; D050296:Microbial Viability; D009154:Mutation; D010587:Phagocytosis; D010767:Phosphorylcholine / Q000378:metabolism; D011008:Pneumococcal Infections / Q000382:microbiology / Q000473:pathology; D017384:Sequence Deletion; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D037521:Virulence Factors; D010767:Phosphorylcholine; D019916:Choline-Phosphate Cytidylyltransferase
keywords: Choline binding proteins; Phosphocholine; Phosphocholine cytidylyltransferase; Virulence