title: Putative cobalt- and nickel-binding proteins and motifs in Streptococcus pneumoniae.
abstract: Cobalt and nickel play important roles in various biological processes. The present work focuses on the enrichment and identification of Co- and Ni-binding motifs and proteins in Gram-positive bacteria. Immobilized metal affinity column (IMAC) was used to partially enrich putative metal-binding proteins and peptides from Streptococcus pneumoniae, and then LTQ-Orbitrap mass spectrometry (MS) was applied to identify and characterize the metal-binding motifs and proteins. In total, 208 and 223 proteins were isolated by Co- and Ni-IMAC columns respectively, in which 129 proteins were present in both preparations. Based on the gene ontology (GO) analysis, the putative metal-binding proteins were found to be mainly involved in protein metabolism, gene expression regulation and carbohydrate metabolism. These putative metal-binding proteins form a highly connected network, indicating that they may synergistically work together to achieve specific biological functions. Putative Co- and Ni-binding motifs were identified with H(X)nH, M(X)nH and H(X)nM derived from the identified 51 Co-binding peptides and 66 Ni-binding peptides. Statistics of frequency of amino acids in the metal-binding motifs showed that cobalt and nickel prefer to bind histidine and methionine, but not cysteine. These results obtained by a systematic metalloproteomic approach provide important clues for the further investigation of metal homeostasis and metal-related virulence of bacteria.
authors.affiliation: Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China. tsunxs@jnu.edu.cn
authors.forename: Xuesong
authors.initials: X
authors.lastname: Sun
authors.forename: Guangchuang
authors.initials: G
authors.lastname: Yu
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Chuanle
authors.initials: C
authors.lastname: Xiao
authors.forename: Xingfeng
authors.initials: X
authors.lastname: Yin
authors.forename: Kun
authors.initials: K
authors.lastname: Cao
authors.forename: Junlong
authors.initials: J
authors.lastname: Han
authors.forename: Qing-Yu
authors.initials: QY
authors.lastname: He
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D003035:Cobalt / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism*; D011485:Protein Binding; D013296:Streptococcus pneumoniae / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003035:Cobalt; D009532:Nickel