Authors: Pisani, F.¹; Italiano, F.²; de Leo, F.³; Gallerani, R.; Rinalducci, S.⁴; Zolla, L.⁴; Agostiano, A.; Ceci, L.R.³; Trotta, M.²

Source: Journal of Applied Microbiology, Volume 106, Number 1, January 2009 , pp. 338-349(12)

Publisher: Wiley-Blackwell

Abstract:

Aims: 

To investigate the surviving capability of Rhodobacter sphaeroides under phototrophic conditions in the presence of high cobalt concentration and its influence on the photosynthetic apparatus biosynthesis. Methods and Results: 

Cells from R. sphaeroides strain R26·1 were grown anaerobically in a medium containing 5·0 mmol l⁻¹ cobalt ions and in a control medium. Metal toxicity was investigated comparing the soluble proteome of Co²⁺-exposed cells and cells grown in control medium by two-dimensional gel electrophoretic analysis. Significant changes in the expression level were detected for 43 proteins, the majority (35) being up-regulated. The enzyme porphobilinogen deaminase (PBGD) was found down-regulated and its activity was investigated. Conclusions: 

The up-regulated enzymes mainly belong to the general category of proteins and DNA degradation enzymes, suggesting that part of the catabolic reaction products can rescue bacterial growth in photosynthetically impaired cells. Furthermore, the down-regulation of PBGD strongly indicates that this key enzyme of the tetrapyrrole and bacteriochlorophyll synthesis is directly involved in the metabolic response. Significance and Impact of the Study: 

Data and experiments show that the cobalt detrimental effect on the photosynthetic growth of R. sphaeroides is associated with an impaired expression and functioning of PBGD.

Keywords: cobalt exposure; photosynthesis; porphobilinogen deaminase; Rhodobacter sphaeroides; 2DE PAGE analysis

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2672.2008.04007.x

Affiliations: 1:  Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Bari, Bari, Italy 2:  Istituto per i Processi Chimico Fisici (CNR), Bari, Italy 3:  Istituto di Biomembrane e Bioenergetica (CNR), Trani and Bari, Italy 4:  Dipartimento di Scienze Ambientali, Università della Tuscia, Viterbo, Italy

Publication date: 2009-01-01

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