title: Genetic structure of three fosmid-fragments encoding 16S rRNA genes of the Miscellaneous Crenarchaeotic Group (MCG): implications for physiology and evolution of marine sedimentary archaea.
abstract: Archaea of the Miscellaneous Crenarchaeotic Group (MCG) exist widely in soil, freshwater and marine sediments of both surface and subsurface. However, current knowledge about this group is limited to its phylogenetic diversity. An archaeal 16S library was constructed from a sediment sample from the South China Sea, which was dominated by MCG and Marine Group I (MG-I). A metagenomic library was constructed from the same sediment sample, and three MCG fosmids (E6-3G, E37-7F and E48-1C) containing 16S rRNA genes were screened. Annotation showed that the three genomic fragments encode a variety of open reading frames (ORFs) that are potentially homologous to important functional genes related to lipid biosynthesis, energy metabolism, and resistance to oxidants. No colinear regions were found between MCG fosmids and reported archaeal genomic fragments or genomes, suggesting that the MCG archaea are quite different from the sequenced archaea in gene arrangement. Analyses of both the phylogenies of 16S rRNA genes and several informational processing genes and nucleotide frequencies showed that MCG archaea are distinct from MG-I plus relatives. In addition, tetranucleotide frequency analysis in combination with phylogenetic analysis suggested that some fragments in the MCG fosmids are probably derived from non-MCG or non-archaeal genomes.
authors: State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan, China.
authors: Ping-Yi
authors: PY
authors: Li
authors: Bin-Bin
authors: BB
authors: Xie
authors: Xi-Ying
authors: XY
authors: Zhang
authors: Qi-Long
authors: QL
authors: Qin
authors: Hong-Yue
authors: HY
authors: Dang
authors: Xu-Min
authors: XM
authors: Wang
authors: Xiu-Lan
authors: XL
authors: Chen
authors: Jun
authors: J
authors: Yu
authors: Yu-Zhong
authors: YZ
authors: Zhang
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D002681:China; D019641:DNA, Archaeal / Q000032:analysis*; D015723:Gene Library; D020459:Genes, rRNA; D020745:Genome, Archaeal; D019015:Geologic Sediments / Q000382:microbiology; D056186:Metagenomics; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology
chemical_list: D019641:DNA, Archaeal; D012336:RNA, Ribosomal, 16S