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R Plasterk

Publications and source records attributed to R Plasterk.

4 recordsLinked to original sources
PubMed2000

Caenorhabditis elegans has a single pathway to target matrix proteins to peroxisomes.

All eukaryotes so far studied, including animals, plants, yeasts and trypanosomes, have two pathways to target proteins to peroxisomes. These two pathways are specific for the two types of peroxisome targeting signal (PTS) present on peroxisomal matrix proteins. Remarkably, the complete genome sequence of Caenorhabditis elegans lacks the genes encoding proteins specific for the PTS2 targeting pathway. Here we show, by expression of green fluorescent protein (GFP) reporters for both pathways, that the PTS2 pathway is indeed absent in C. elegans. Lack of this pathway in man causes severe disease due to mislocalization of PTS2-containing proteins. This raises the question as to how C. elegans has accommodated the absence of the PTS2 pathway. We found by in silico analysis that C. elegans orthologues of PTS2-containing proteins have acquired a PTS1. We propose that switching of targeting signals has allowed the PTS2 pathway to be lost in the phylogenetic lineage leading to C. elegans.

Alkyl and Aryl Transferases↗
PubMed1993

Interactions between HIV-1 nucleocapsid protein and viral DNA may have important functions in the viral life cycle.

In the virion core of retroviruses, the genomic RNA is tightly associated with nucleocapsid (NC) protein molecules, forming the nucleocapsid structure. NC protein, a highly basic protein with two zinc fingers, is indispensable for RNA dimerization, encapsidation and the initiation of reverse transcription in avian, murine and human retroviruses. Here we show that NC protein of HIV-1 (NCp7) and NCp7 mutants bind to DNA fragments representing proviral DNA sequences, forming stable complexes. NCp7 and NCp7 mutants form high molecular weight complexes with large DNA fragments and show cooperativity in binding to the DNAs. It appears that the conserved basic residues, and not the zinc fingers, are important for complex formation. In addition, NCp7 and several NCp7 mutants protect DNAs from nuclease digestion while the DNA ends appear to be poorly protected. NCp7 has been found to bind to strong stop cDNA, the initial product of reverse transcription, and to promote the annealing of this cDNA to HIV-1 RNA corresponding to the 3' end of the genome. In addition, NCp7 slightly stimulates an in vitro IN cleavage assay. These results indicate that the interactions between NCp7 and proviral DNA may be important during provirus synthesis and/or prior to integration.

Amino Acid Sequence↗
PubMed1984

A Mu gin complementing function and an invertible DNA region in Escherichia coli K-12 are situated on the genetic element e14.

The Gin product catalyzes an inversion of 3,000 base pairs of DNA in the genome of bacteriophage Mu. The orientation of the invertible of G-region determines the host range of the phage. Gin- mutants are complemented by a host function in strain HB101 and several other Escherichia coli K-12 strains. At least three clones in the E. coli gene bank described previously (L. Clarke and J. Carbon, Cell 9:91-99, 1976) contained the gin complementing function. This function, which we named pin, catalyzes an inversion of 1,800 base pairs in the adjacent DNA. The invertible region, named the P-region, together with pin, was further subcloned on pBR322. Conjugation and transduction experiments mapped the pin gene between the genes purB and fabD near position 25 on the E. coli chromosome. Also situated in this region is e14, a cryptic, UV- excisable , genetic element (A. Greener and C.W. Hill, J. Bacteriol . 144:312-321, 1980). We demonstrated that pin and the P-region are part of e 14. The e 14 element was cloned on pBR322 by genetic manipulation techniques in vivo. It has the properties of a defective prophage containing integration and excision functions and a SOS-sensitive repressor.

Attachment Sites, Microbiological↗