Figure 1.
Demethylation and C1 oxidation regions of the strain HTCC1062 genome.
(A) formate dehydrogenase; (B) methanol metabolism; (C) methylamine oxidation; (D) glycine betaine oxidation; (E) aminomethyltransferases (Asterisk). fdhF, formate dehydrogenase, alpha subunit; fdsB, NAD-dependent formate dehydrogenase, beta subunit; fdhD, formate dehydrogenase, chain D; mobA, molybdopterin-guanine dinucleotide biosynthesis protein A; moeA, molybdopterin biosynthesis protein; fhs, formate-THF ligase; SAR11_1286, putative glutamine amidotransferase; Fe-ADH, iron-containing alcohol dehydrogenase; ssdH, aldehyde dehydrogenase family; SAR11_1289, short chain dehydrogenase; soxB, sarcosine oxidase; soxD & soxD2, sarcosine oxidase delta chain; soxA & soxA2, sarcosine oxidase alpha chain; soxG & soxG2, sarcosine oxidase gamma subunit; soxB2, sarcosine oxidase beta subunit; glxBCD, glutamate synthase; glnT, Glutamine synthetase III (putative gamma-glutamylmethylamide synthetase); bhmT, betaine-homocysteine methyltransferase; sardh, sarcosine dehydrogenase; dmgdh, dimethylglycine dehydrogenase; gcvT, glycine system cleavage T-protein; gcvH, glycine cleavage H-protein; gcvP, glycine cleavage P-protein; dmdA, dimethylsulfoniopropionate-dependent demethylase; mhpC, hydrolase, alpha/beta hydrolase fold family; fadD, CoA activator for DMSP beta oxidation; mmgC, acyl-CoA dehydrogenase for DMSP beta oxidation; metF, methylene-THF reductase; opuAB, glycine betaine transport system permease protein; opuAA, glycine betaine transport ATP-binding protein; opuAC, substrate-binding region of ABC-type glycine betaine transport system; SAR11_1265 & SAR11_1303, gcvT-like aminomethyltransferase protein; SAR11_1304, monomeric sarcosine oxidase. Colors correspond to pathways in Figure 2.
Figure 2.
Proposed C1 and methylated compound oxidation pathways in SAR11 Group Ia.
(A) THF-linked oxidation pathway; (B) methanol oxidation pathway; (C) glycine betaine demethylation and oxidation; (D) methylamine oxidation pathways; (E) TMAO degradation pathway; (F) glycine cleavage pathway; (G) DMSP demethylation. Note: ? - unidentified metabolic processes/enzymes; * - spontaneous reaction; † - two paralogous operons.
Table 1.
Distribution of genes involved in C1 metabolism among three SAR11 Ia genomes.
Figure 3.
Phylogenetic tree of Fe-ADH proteins.
Coloration is according to 16S rRNA gene phylogeny, as shown in the boxed legend. Bootstrap values were omitted for clarity; nodes with less than 60% support were collapsed. Arrows indicate Fe-ADH proteins for which methanol dehydrogenase activity has been demonstrated experimentally. Scale bar = 0.4 changes per position.
Table 2.
ATP response of starved cells to addition of various alcoholsa.
Table 3.
ATP response of starved cells to addition of C1 and methylated compoundsa.
Figure 4.
Phylogeny of SAR11 AMT proteins.
Four paralogous AMTs in HTCC1062 were placed into three functional subgroups: DmdA-like, GcvT, and an AMT of unknown function. All four AMTs were also identified in HTCC1002 and HTCC7211 genomes. This phylogenetic tree was generated using the neighbor-joining method. Bootstrap values are based on 100 iterations.
Figure 5.
14C-labeled compound utilization by HTCC1062 in culture.
HTCC1062 Cells from log phase were collected and resuspended in artificial seawater media (ASW). Radioisotope assays were conducted at room temperature (22°C) in ASW amended with (A) 1 µM 14C-[methyl]-GBT; (B) 5 µM 14C-TMA; (C) 20 µM 14C-methanol; or (D) 100 nM 14C-formaldehyde. Where not visible, error bars are smaller than the size of the symbols.
Figure 6.
Utilization of 14C-labeled C1 and methylated compounds by bacterioplankton in the western Sargasso Sea.
The oxidation and incorporation rates were calculated from the initial linear part of each curve. Rate of 14C-compound oxidation to 14CO2 (▪); rate of 14C-compounds incorporation into biomass (□).