Watsuji TO

References (2)

Title : Allying with armored snails: the complete genome of gammaproteobacterial endosymbiont - Nakagawa_2014_ISME.J_8_40
Author(s) : Nakagawa S , Shimamura S , Takaki Y , Suzuki Y , Murakami S , Watanabe T , Fujiyoshi S , Mino S , Sawabe T , Maeda T , Makita H , Nemoto S , Nishimura S , Watanabe H , Watsuji TO , Takai K
Ref : Isme J , 8 :40 , 2014
Abstract : Deep-sea vents harbor dense populations of various animals that have their specific symbiotic bacteria. Scaly-foot gastropods, which are snails with mineralized scales covering the sides of its foot, have a gammaproteobacterial endosymbiont in their enlarged esophageal glands and diverse epibionts on the surface of their scales. In this study, we report the complete genome sequencing of gammaproteobacterial endosymbiont. The endosymbiont genome displays features consistent with ongoing genome reduction such as large proportions of pseudogenes and insertion elements. The genome encodes functions commonly found in deep-sea vent chemoautotrophs such as sulfur oxidation and carbon fixation. Stable carbon isotope ((13)C)-labeling experiments confirmed the endosymbiont chemoautotrophy. The genome also includes an intact hydrogenase gene cluster that potentially has been horizontally transferred from phylogenetically distant bacteria. Notable findings include the presence and transcription of genes for flagellar assembly, through which proteins are potentially exported from bacterium to the host. Symbionts of snail individuals exhibited extreme genetic homogeneity, showing only two synonymous changes in 19 different genes (13 810 positions in total) determined for 32 individual gastropods collected from a single colony at one time. The extremely low genetic individuality in endosymbionts probably reflects that the stringent symbiont selection by host prevents the random genetic drift in the small population of horizontally transmitted symbiont. This study is the first complete genome analysis of gastropod endosymbiont and offers an opportunity to study genome evolution in a recently evolved endosymbiont.
ESTHER : Nakagawa_2014_ISME.J_8_40
PubMedSearch : Nakagawa_2014_ISME.J_8_40
PubMedID: 23924784
Gene_locus related to this paper: 9gamm-s6bga5

Title : Genome sequence of Symbiobacterium thermophilum, an uncultivable bacterium that depends on microbial commensalism - Ueda_2004_Nucleic.Acids.Res_32_4937
Author(s) : Ueda K , Yamashita A , Ishikawa J , Shimada M , Watsuji TO , Morimura K , Ikeda H , Hattori M , Beppu T
Ref : Nucleic Acids Research , 32 :4937 , 2004
Abstract : Symbiobacterium thermophilum is an uncultivable bacterium isolated from compost that depends on microbial commensalism. The 16S ribosomal DNA-based phylogeny suggests that this bacterium belongs to an unknown taxon in the Gram-positive bacterial cluster. Here, we describe the 3.57 Mb genome sequence of S.thermophilum. The genome consists of 3338 protein-coding sequences, out of which 2082 have functional assignments. Despite the high G + C content (68.7%), the genome is closest to that of Firmicutes, a phylum consisting of low G + C Gram-positive bacteria. This provides evidence for the presence of an undefined category in the Gram-positive bacterial group. The presence of both spo and related genes and microscopic observation indicate that S.thermophilum is the first high G + C organism that forms endospores. The S.thermophilum genome is also characterized by the widespread insertion of class C group II introns, which are oriented in the same direction as chromosomal replication. The genome has many membrane transporters, a number of which are involved in the uptake of peptides and amino acids. The genes involved in primary metabolism are largely identified, except those that code several biosynthetic enzymes and carbonic anhydrase. The organism also has a variety of respiratory systems including Nap nitrate reductase, which has been found only in Gram-negative bacteria. Overall, these features suggest that S.thermophilum is adaptable to and thus lives in various environments, such that its growth requirement could be a substance or a physiological condition that is generally available in the natural environment rather than a highly specific substance that is present only in a limited niche. The genomic information from S.thermophilum offers new insights into microbial diversity and evolutionary sciences, and provides a framework for characterizing the molecular basis underlying microbial commensalism.
ESTHER : Ueda_2004_Nucleic.Acids.Res_32_4937
PubMedSearch : Ueda_2004_Nucleic.Acids.Res_32_4937
PubMedID: 15383646
Gene_locus related to this paper: symth-metx , symth-q67kd5 , symth-q67kg6 , symth-q67kl6 , symth-q67km7 , symth-q67lu3 , symth-q67mi3 , symth-q67mk6 , symth-q67mr3 , symth-q67n56 , symth-q67nt3 , symth-q67pl6 , symth-q67qv2 , symth-q67r02 , symth-q67r99 , symth-q67ra1 , symth-q67ri0 , symth-q67rl1 , symth-q67ru9 , symth-q67s20 , symth-q67sr9 , symth-q67sv7 , symth-q67t46