Bacterial signaling and studying diseases through exome sequencing, in my picks of the week from RB

Another week has gone by and some very interesting molbio blog posts have been aggregated to Researchblogging.org. Every week [see my opening post on the matter], I'll select some blog posts I consider particularly interesting in the field of molecular biology [see here to get a sense of the criteria that will be used], briefly describe them and list them here for you to check out.

Note that I'm only taking into consideration the molbio-related blog posts aggregated under "Biology".

Congratulations to everyone who got their post selected.

1) All cells (including free-living organisms), can modulate their gene expression profiles in response to changes in their surroundings.

In bacteria, extracellular signals are transduced into the cell predominantly by two-component systems, but “bacteria also contain multi-component systems, for both inter- and intra-cellular signaling”.
Lab Rat discusses a recent article presenting a comprehensive census of signal transduction proteins encoded in 167 bacterial and archaeal genomes, which reveals some very interesting trends regarding their phylogenetic distribution and numbers. It also points to some unique features exclusive to bacterial signaling systems.

From the article:

“The complexity of signaling systems differs even among closely related organisms. Still, it usually can be correlated with the phylogenetic position of the organism, its lifestyle, and typical environmental challenges it encounters”

2. Keith Robison at Omics! Omics! discusses a new paper reporting the first application of exome sequencing to uncover the affected gene responsible for a rare mendelian disorder of unknown cause, Miller syndrome. The authors identified a single candidate gene, DHODH, which encodes a key enzyme in the pyrimidine de novo biosynthesis pathway.

From the article:

(…) deep resequencing of all human genes for discovery of allelic variants could potentially identify the gene underlying any given rare monogenic disease. Massively parallel DNA sequencing technologies have rendered the whole-genome resequencing of individual humans increasingly practical, but cost remains a key consideration. An alternative approach involves the targeted resequencing of all protein-coding subsequences (that is, the exome), which requires 5% as much sequencing as a whole human genome.

Keith comments on the results, methodology and on the economic feasibility to use this approach to study the genetic basis of a large number of still uncharacterized rare diseases.

That's it for this week. Stay tuned for more MolBio Research Highlights!

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Some of the articles discussed in this week's selected posts:

Galperin MY (2005). A census of membrane-bound and intracellular signal transduction proteins in bacteria: bacterial IQ, extroverts and introverts. BMC microbiology, 5 PMID: 15955239

Ng, S., Buckingham, K., Lee, C., Bigham, A., Tabor, H., Dent, K., Huff, C., Shannon, P., Jabs, E., Nickerson, D., Shendure, J., & Bamshad, M. (2009). Exome sequencing identifies the cause of a mendelian disorder Nature Genetics DOI: 10.1038/ng.499