SRA

Multiple species of bacteria oxidize methane in the environment after it is produced by anaerobic ecosystems. These organisms provide a carbon and energy source for species that cannot oxidize methane themselves, thereby serving a key role in these niches while also sequestering this potent greenhouse gas before it enters the atmosphere. Deciphering the molecular details of how methane-oxidizing bacteria interact in the environment enables us to understand an important aspect that shapes the structure and function these communities. Here we show that many members of the Methylomonas genus possess a LuxR-type acyl-homoserine lactone (acyl-HSL) receptor/transcription factor highly homologous to MbaR from the quorum sensing (QS) system of Methylobacter tundripaludum, another methane-oxidizer that has been isolated from the same environment. We reconstitute this detection system in Escherichia coli and also use mutant and transcriptomic analysis to show that the receptor from Methylomonas species strain LW13 (LW13) is active and alters LW13 gene expression in response to the acyl-HSL produced by M. tundripaludum. These findings provide a molecular mechanism for how two species of bacteria that may compete for resources in the environment can interact in a specific manner through a chemical signal. Overall design: In order to determine which genes MmsR regulates in response to acyl-HSL signal, we compared the transcriptome of exponentially growing LW13 in the presence or absence of 3-OH-C10-HSL. As a control for gene changes that are not the result of signal binding to MmsR, we constructed an unmarked, in-frame deletion of mmsR (?mmsR) and also compared the transcriptome of this strain in the presence and absence of signal. For each condition, we sequenced the transcriptomes of two biological replicates.