Genome
The genome of P. ubique strain HTCC1062 was completely sequenced in 2005 showing that P. ubique has the smallest genome (1,308,759 bp) of any free living organism encoding only 1,354 open reading frames (1,389 genes total). The only species with smaller genomes are endocellular symbionts and parasites, such as Mycoplasma genitalium or Nanoarchaeum equitans It has the smallest number of open reading frames of any free living organism, and the shortest intergenic spacers, but it still has metabolic pathways for all 20 amino acids and most co-factors. Its genome has been streamlined. This streamlining concept is important because it reduces the amount of energy required for cell replication. P. ubique saves energy by using the base pairs A and T (≈70.3% of all base pairs) because they contain less nitrogen, a resource that is hard for organisms to acquire.
Non-coding RNAs have been identified in P. ubique through a bioinformatics screen of the published genome and metagenomic data. Examples of ncRNA found in this organisms include the SAM-V riboswitch, and other cis-regulatory elements like the rpsB motif. Another example of an important ncRNA in P. ubique and other SAR11 clade members is a conserved, glycine-activated riboswitch on malate synthase, putatively leading to "functional auxotrophy" for glycine or glycine precursors in order to achieve optimal growth.
It is found to have proteorhodopsin genes, which help power light-mediated proton pumps. Subtle differences arise in the expression of its codon sequences when it is subjected to either light or dark treatments. More genes for oxidative phosphorylation are expressed when it is subject to darkness.
Read more about this topic: Pelagibacter Ubique