New Shewanella papers

Hello Shewanella folks,

Here are a couple of new papers from the Shewanella Fed. I haven’t thoroughly read them yet, but there are some interesting findings nestled in each paper.

1.  McLean JS, Pinchuk GE, Geydebrekht OV, Bilskis CL, Zakrajsek BA, Hill EA, Saffarini DA, Romine MF, Gorby YA, Fredrickson JK, Beliaev AS.
Oxygen-dependent autoaggregation in Shewanella oneidensis MR-1.
Environ Microbiol. 2008 Apr 9 PMID: 18412550

2: Yang Y, Harris DP, Luo F, Wu L, Parsons AB, Palumbo AV, Zhou J.
Characterization of the Shewanella oneidensis Fur gene: roles in iron and acid
tolerance response.
BMC Genomics. 2008;9 Suppl 1:S11. PMID: 18366600

Happy reading!

 

CymA and iron reductase activity?

Interesting paper on the tetraheme cytochrome has just been published. Authors show that the CymA cytochrome has iron reductase activity when expressed in E. coli. They propose that this has given E. coli the ability to respire iron(III). That is, E. coli can conserve energy from reducing iron and grow on it too. This is normally not the case. Here is the link to the paper in Pubmed:

Dissimilatory iron reduction in Escherichia coli: identification of CymA of Shewanella oneidensis and NapC of E. coli as ferric reductases.

Gescher JS, Cordova CD, Spormann AM.

http://www.ncbi.nlm.nih.gov/pubmed/18394146?dopt=Abstract

 

New paper on an arsenate respiring bacterium, Alkaliphilus oremlandii

Stolz and colleagues (Duquesne University) published a recent paper on the characterization of an arsenate respiring bacterium isolated from the Ohio River. The microbe, Alkaliphilus oremlandii strain OhILAs, was named in honor of the grandfather of arsenic-respiring bacteria Dr. Ron Oremland. Here is the PubMed link:

Fisher et al. (2008) Transformation of Inorganic and Organic Arsenic by Alkaliphilus oremlandii sp. nov. Strain OhILAs. Ann N Y Acad Sci. 1125:230-41.

The strain is gram positive and appears to tolerate and grow quite well on arsenic. Definitely a paper we should all read.

 

Arsenic can cause ED?

I thought this was an April Fools joke. However, according to a recent article in Environmental Health Perspectives, arsenic exposure in drinking water is a risk factor for erectile dysfunction. Here is the link to the abstract:

Fang et al. “Risk of Erectile Dysfunction Induced by Arsenic Exposure through Well Water Consumption in Taiwan” Environmental Health Perspectives Volume 116, Number 4, April 2008

Linking arsenic to ED seems crazy but in the intro the authors mention that ED is linked to cardiovascular diseases, which is also influenced by arsenic exposure too. If you make the connection between arsenic and cardiovascular disease therefore, ED could be another symptom of arsenic exposure. We’ll see how this plays out in long run.

 

Arsenic Crisis in Bangladesh

Here is an interesting commentary on how the arsenic crisis in Bangladesh came to be. If the sources are true it’s an amazing story with a sad outcome:

http://www.unesco.org/courier/2001_01/uk/planet.htm

 

Isotopic labeling of Geobacter cytochromes

This looks like an interesting paper on N-15 labeling of c-type cytochromes:

Isotopic labeling of c-type multiheme cytochromes overexpressed in E. coli.
Fernandes et al. 2008

Progresses made in bacterial genome sequencing show a remarkable profusion of multiheme c-type cytochromes in many bacteria, highlighting the importance of these proteins in different cellular events. However, the characterization of multiheme cytochromes has been significantly retarded by the numerous experimental challenges encountered by researchers who attempt to overexpress these proteins, especially if isotopic labeling is required. Here we describe a methodology for isotopic labeling of multiheme cytochromes c overexpressed in Escherichia coli, using the triheme cytochrome PpcA from Geobacter sulfurreducens as a model protein. By combining different strategies previously described and using E. coli cells containing the gene coding for PpcA and the cytochrome c maturation gene cluster, an experimental labeling methodology was developed that is based on two major aspects: (i) use of a two-step culture growth procedure, where cell growth in rich media was followed by transfer to minimal media containing (15)N-labeled ammonium chloride, and (ii) incorporation of the heme precursor delta-aminolevulinic acid in minimal culture media. The yields of labeled protein obtained were comparable to those obtained for expression of PpcA in rich media. Proper protein folding and labeling were confirmed by UV-visible and NMR spectroscopy. To our knowledge, this is the first report of a recombinant multiheme cytochrome labeling and it represents a major breakthrough for functional and structural studies of multiheme cytochromes.

This looks really useful for making structure predictions or even looking at protein-protein interactions.

-chad

 

Lab Meeting Paper for 3/20/2008

Suggested reading: “Shewanella secretes flavins that mediate extracellular electron transfer” by Bond and Gralnick labs. Here is the url: http://www.pnas.org/cgi/content/short/105/10/3968