Stress proteins in the cytoplasmic membrane fraction of Bacillus subtilis.

Stress proteomes of the cytoplasmic membrane fraction of Bacillus subtilis trp (C2)-exposed to acid pH and ethanol were characterized. Although these stress factors impair the cell function in a specific manner, they share the ability to denature proteins. Therefore, specific and general stress proteins in the membranes were investigated. Both ethanol (3 %) and pH 5.0 increase the doubling time from 17 to 25 min. Isolated cytoplasmic membranes were subjected to an optimized 2D PAGE analysis which permitted the separation and analysis of ≈450 distinct protein spots. Two alternative methods of protein detection were compared, i.e. silver staining and (35)S-L-methionine pulse labeling; the stress induced proteins were identified by MALDI-TOF MS. After ethanol stress, five proteins were increased, viz. YdaP, Ctc, YfhM, YjcH and YwaC. Acid stress proteins were AcoB, YkwC, SodA, YjcH and YwaC. Proteins YjcH and YwaC were increased after ethanol as well as acid pH treatment.

Comparative study of the life cycle dependent post-translation modifications of protein synthesis elongation factor Tu present in the membrane proteome of streptomycetes and mycobacteria.

We present the results of analysis of membrane phosphoproteomes from individual morphological stages of Streptomyces coelicolor that reflect developmentally dependent heterogeneity and phosphorylation of intrinsic and externally added purified Strepomyces aureofaciens EF-Tu. Fast growing nonpathogenic Mycobacterium smegmatis was used as a non-differentiating actinomycetes comparative model. Streptomycetes membrane fraction was found to contain protein kinase(s) catalyzing phosphorylation of both its own and an externally added EF-Tu, whereas Mycobacterium membrane fraction contains protein kinase phosphorylating only its own EF-Tu.