Biomedical subjects

Maximino Manzanera

Publications and source records attributed to Maximino Manzanera.

5 recordsLinked to original sources

PubMed2006

Macroscopic 2D networks self-assembled from nanometer-sized protein/DNA complexes.

We demonstrate the self-assembly of DNA and DNA binding proteins into two-dimensional networks that are then addressable by sending a second protein to a specific recognition site on the DNA network. These networks cover centimeters in area but can be addressed with nanometer precision. This hierarchical self-assembly of specific DNA protein complexes will be the basis for complex positioning of single molecules in two and three dimensions.

Base Sequence↗

PubMed2004

High survival and stability rates of Escherichia coli dried in hydroxyectoine.

The tetrahydropyramidine hydroxyectoine acts as an osmolyte in a range of bacterial species, but its use as a desiccation protectant is less well explored. Recently, it was demonstrated that hydroxyectoine provides effective stabilisation of the Gram-negative species Pseudomonas putida, which is only relatively poorly preserved by the better-characterised protectant, trehalose. It is now shown that hydroxyectoine also protects the paradigmatic bacterium, Escherichia coli: osmotically-preconditioned E. coli dried in hydroxyectoine exhibited a high degree of desiccation tolerance, similar to that achieved using trehalose in this species. Hydroxyectoine is apparently accumulated from hypersaline medium in preference to trehalose biosynthesis, but E. coli loaded with hydroxyectoine in this way showed reduced stability in the dry state. This suggests that, although both hydroxyectoine and trehalose perform equally well as extracellular protectants, trehalose is preferred for intracellular protection.

Amino Acids, Diamino↗

PubMed2002

Species-specific repetitive extragenic palindromic (REP) sequences in Pseudomonas putida.

Pseudomonas putida KT2440 is a soil bacterium that effectively colonises the roots of many plants and degrades a variety of toxic aromatic compounds. Its genome has recently been sequenced. We describe that a 35 bp sequence with the structure of an imperfect palindrome, originally found repeated three times downstream of the rpoH gene terminator, is detected more than 800 times in the chromosome of this strain. The structure of this DNA segment is analogous to that of the so-called enterobacteriaceae repetitive extragenic palindromic (REP) sequences, although its sequence is different. Computer-assisted analysis of the presence and distribution of this repeated sequence in the P.putida chromosome revealed that in at least 80% of the cases the sequence is extragenic, and in 82% of the cases the distance of this extragenic element to the end of one of the neighbouring genes was <100 bp. This 35 bp element can be found either as a single element, as pairs of elements, or sometimes forming clusters of up to five elements in which they alternate orientation. PCR scanning of chromosomes from different isolates of Pseudomonas sp. strains using oligonucleotides complementary to the most conserved region of this sequence shows that it is only present in isolates of the species P.putida. For this reason we suggest that the P.putida 35 bp element is a distinctive REP sequence in P.putida. This is the first time that REP sequences have been described and characterised in a group of non-enterobacteriaceae.

Base Sequence↗

PubMed2002

Cross-regulation between a novel two-component signal transduction system for catabolism of toluene in Pseudomonas mendocina and the TodST system from Pseudomonas putida.

The tmoABCDEF genes encode the toluene-4-monooxygenase from Pseudomonas mendocina KR1. Upstream from the tmoA gene an open reading frame, tmoX, encoding a protein 83% identical to TodX (todX being the initial gene in the todXFC1C2BADEGIH operon from Pseudomonas putida DOT-T1E) was found. The tmoX gene is also the initial gene in the tmoXABCDEF gene cluster. The transcription initiation point from the tmoX promoter was mapped, and the sequence upstream revealed striking identity with the promoter of the tod operon of P. putida. The tod operon is regulated by a two-component signal transduction system encoded by the todST genes. Two novel genes from P. mendocina KR1, tmoST, were rescued by complementation of a P. putida DOT-T1E todST knockout mutant, whose gene products shared about 85% identity with TodS-TodT. We show that transcription from P(tmoX) and P(todX) can be mediated by TmoS-TmoT or TodS-TodT, in the presence of toluene, revealing cross-regulation between these two catabolic pathways.

Bacterial Proteins↗

PubMed2001

Molecular characterization of Pseudomonas putida KT2440 rpoH gene regulation.

The rpoH gene of Pseudomonas putida KT2440 encoding the heat-shock sigma factor sigma(32) was cloned and sequenced, and the translated gene product was predicted to be a protein of 32.5 kDa. The unambiguous role of the gene as a sigma factor was confirmed because the cloned P. putida gene complemented the growth defect, at 37 and 42 degrees C, of an Escherichia coli rpoH mutant strain. Primer extension analysis showed that in P. putida the rpoH gene is expressed from three promoters in cells growing at 30 degrees C. Two of them, P1 and P3, share homology with the sigma(70)-dependent promoters, while the third one, P2, shows a typical sigma(24)-consensus sequence. The pattern of transcription initiation of the rpoH gene did not change in response to different stresses, i.e. a sudden heat shock or the addition of aromatic compounds. However, the predicted secondary structure of the 5' region of the mRNA derived from the three different promoters suggests regulation at the level of translation efficiency and/or mRNA half-life. An inverted repeat sequence located 20 bp downstream of the rpoH stop codon was shown to function as a terminator in vivo in P. putida growing at temperatures from 18 to 42 degrees C.

Base Sequence↗