Biomedical subjects

Nicole Hansmeier

Publications and source records attributed to Nicole Hansmeier.

5 recordsLinked to original sources

PubMed2006

The cytosolic, cell surface and extracellular proteomes of the biotechnologically important soil bacterium Corynebacterium efficiens YS-314 in comparison to those of Corynebacterium glutamicum ATCC 13032.

Reference maps of the cytosolic, cell surface and extracellular proteome fractions of the amino acid-producing soil bacterium Corynebacterium efficiens YS-314 were established. The analysis window covers a pI range from 3 to 7 along with a molecular mass range from 10 to 130 kDa. After second-dimensional separation on SDS-PAGE and Coomassie staining, computational analysis detected 635 protein spots in the cytosolic proteome fraction, whereas 76 and 102 spots were detected in the cell surface and extracellular proteomes, respectively. By means of MALDI-TOF-MS and tryptic peptide mass fingerprinting, 164 cytosolic proteins, 49 proteins of the cell surface and 89 extracellular protein spots were identified, representing in total 177 different proteins. Additionally, reference maps of the three cellular proteome fractions of the close phylogenetic relative Corynebacterium glutamicum ATCC 13032 were generated and used for comparative proteomics. Classification according to the Clusters of Orthologous Groups of proteins scheme and abundance analysis of the identified proteins revealed species-specific differences. The high abundance of molecular chaperones and amino acid biosynthesis enzymes in C. efficiens points to environmental adaptations of this recently discovered amino acid-producing bacterium.

Amino Acid Sequence↗

PubMed2006

Mapping and comprehensive analysis of the extracellular and cell surface proteome of the human pathogen Corynebacterium diphtheriae.

Secreted proteins of the human pathogen Corynebacterium diphtheriae might be involved in important pathogen-host cell interactions. Here, we present the first systematic reference map of the extracellular and cell surface proteome fractions of the type strain C. diphtheriae C7s(-)tox-. The analysis window of 2-DE covered the pI range from 3 to 10 along with a MW range from 8 to 150 kDa. Computational analysis of the 2-D gels detected almost 150 protein spots in the extracellular proteome fraction and about 80 protein spots of the cell surface proteome. MALDI-TOF-MS and PMF with trypsin unambiguously identified 107 extracellular protein spots and 53 protein spots of the cell surface, representing in total 85 different proteins of C. diphtheriae C7s(-)tox-. Several of the identified proteins are encoded by pathogenicity islands and might represent virulence factors of C. diphtheriae. Additionally, four solute-binding proteins (HmuT, Irp6A, CiuA, and FrgD) of different iron ABC transporters were identified, with the hitherto uncharacterized FrgD protein being the most abundant one of the cell surface proteome of C. diphtheriae C7s(-)tox-.

Amino Acid Sequence↗

PubMed2006

The surface (S)-layer gene cspB of Corynebacterium glutamicum is transcriptionally activated by a LuxR-type regulator and located on a 6 kb genomic island absent from the type strain ATCC 13032.

The surface (S)-layer gene region of the Gram-positive bacterium Corynebacterium glutamicum ATCC 14067 was identified on fosmid clones, sequenced and compared with the genome sequence of C. glutamicum ATCC 13032, whose cell surface is devoid of an ordered S-layer lattice. A 5.97 kb DNA region that is absent from the C. glutamicum ATCC 13032 chromosome was identified. This region includes cspB, the structural gene encoding the S-layer protomer PS2, and six additional coding sequences. PCR experiments demonstrated that the respective DNA region is conserved in different C. glutamicum wild-type strains capable of S-layer formation. The DNA region is flanked by a 7 bp direct repeat, suggesting that illegitimate recombination might be responsible for gene loss in C. glutamicum ATCC 13032. Transfer of the cloned cspB gene restored the PS2(-) phenotype of C. glutamicum ATCC 13032, as confirmed by visualization of the PS2 proteins by SDS-PAGE and imaging of ordered hexagonal S-layer lattices on living C. glutamicum cells by atomic force microscopy. Furthermore, the promoter of the cspB gene was mapped by 5' rapid amplification of cDNA ends PCR and the corresponding DNA fragment was used in DNA affinity purification assays. A 30 kDa protein specifically binding to the promoter region of the cspB gene was purified. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry and peptide mass fingerprinting of the purified protein led to the identification of the putative transcriptional regulator Cg2831, belonging to the LuxR regulatory protein family. Disruption of the cg2831 gene in C. glutamicum resulted in an almost complete loss of PS2 synthesis. These results suggested that Cg2831 is a transcriptional activator of cspB gene expression in C. glutamicum.

Bacterial Proteins↗

PubMed2005

Role of the regulatory gene rirA in the transcriptional response of Sinorhizobium meliloti to iron limitation.

A regulatory network of Sinorhizobium meliloti genes involved in adaptation to iron-limiting conditions and the involvement of the rhizobial iron regulator gene (rirA) were analyzed by mutation and microarray analyses. A constructed S. meliloti rirA mutant exhibited growth defects and enhanced H2O2 sensitivity in the presence of iron, but symbiotic nitrogen fixation was not affected. To identify iron-responsive and RirA-regulated S. meliloti genes, a transcriptome approach using whole-genome microarrays was used. Altogether, 45 genes were found to be jointly derepressed by mutation of rirA and under different iron-limited conditions. As expected, a number of genes involved in iron transport (e.g., hmuPSTU, shmR, rhbABCDEF, rhtX, and rhtA) and also genes with predicted functions in energy metabolism (e.g., fixN3, fixP3, and qxtAB) and exopolysaccharide production (e.g., exoY and exoN) were found in this group of genes. In addition, the iron deficiency response of S. meliloti also involved rirA-independent expression changes, including repression of the S. meliloti flagellar regulon. Finally, the RirA modulon also includes genes that are not iron responsive, including a gene cluster putatively involved in Fe-S cluster formation (sufA, sufS, sufD, sufC, and sufB).

Bacterial Proteins↗

PubMed2004

Classification of hyper-variable Corynebacterium glutamicum surface-layer proteins by sequence analyses and atomic force microscopy.

The structural S-layer proteins of 28 different Corynebacterium glutamicum isolates have been analyzed systematically. Treatment of whole C. glutamicum cells with detergents resulted in the isolation of S-layer proteins with different apparent molecular masses, ranging in size from 55 to 66 kDa. The S-layer genes analyzed were characterized by coding regions ranging from 1,473 to 1,533 nucleotides coding for S-layer proteins with a size of 490-510 amino acids. Using PCR techniques, the corresponding S-layer genes of the 28 C. glutamicum isolates were all cloned and sequenced. The deduced amino acid sequences of the S-layer proteins showed identities between 69 and 98% and could be grouped into five phylogenetic classes. Furthermore, sequence analyses indicated that the S-layer proteins of the analyzed C. glutamicum isolates exhibit a mosaic structure of highly conserved and highly variable regions. Several conserved regions were assumed to play a key role in the formation of the C. glutamicum S-layers. Especially the N-terminal signal peptides and the C-terminal anchor sequences of the S-layer proteins showed a nearly perfect amino acid sequence conservation. Analyses by atomic force microscopy revealed a committed hexagonal structure. Morphological diversity of the C. glutamicum S-layers was observed in a class-specific unit cell dimension (ranging from 15.2 to 17.4 nm), which correlates with the sequence similarity-based classification. It could be demonstrated that differences in the primary structure of the S-layer proteins were reflected by the S-layer morphology.

Amino Acid Sequence↗