ABSTRACT
CCCH zinc finger proteins (ZC3Hs) are a novel class of RNA-binding protein involved in post-transcriptional mechanisms controlling gene expression. We show TbZC3H20 from Trypanosoma brucei, the causative agent of sleeping sickness and other diseases, stabilizes two developmentally regulated transcripts encoding a mitochondrial carrier protein (MCP12) and trans-sialidase (TS-like E). TbZC3H20 is shown to be an RNA-binding protein that is enriched in insect procyclic form T. brucei and is the first ZC3H discovered controlling gene expression through modulating mRNA abundance in trypanosomes. Previous studies have demonstrated that RNA recognition motif-containing and PUF family RNA-binding proteins can control gene expression by stabilizing specific target mRNA levels. This work is the first to describe a ZC3H stabilizing rather than destabilizing target mRNAs as a regulatory mechanism and the first report of a ZC3H regulating a gene encoding a mitochondrial protein. This suggests a broader role for ZC3Hs in post-transcriptional regulation of gene expression than previously thought.
Subject(s)
Protozoan Proteins/metabolism , RNA-Binding Proteins/metabolism , Trypanosoma brucei brucei/metabolism , Gene Expression Regulation/physiology , Mitochondrial Proteins/biosynthesis , Mitochondrial Proteins/genetics , Protozoan Proteins/genetics , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , RNA, Protozoan/biosynthesis , RNA, Protozoan/genetics , RNA-Binding Proteins/genetics , Trypanosoma brucei brucei/genetics , Zinc Fingers/physiologyABSTRACT
A species of the hyper-parasitic bacterium Pasteuria was isolated from the root-knot nematode Meloidogyne ardenensis infecting the roots of ash (Fraxinus excelsior). It is morphologically different from some other Pasteuria pathogens of nematodes in that the spores lack a basal ring on the ventral side of the spore and have a unique clumping nature. Transmission electron microscopy (TEM) showed that the clumps of spores are not random aggregates but result from the disintegration of the suicide cells of the thalli. Sporulation within each vegetative mycelium was shown to be asynchronous. In addition to the novel morphological features 16S rRNA sequence analysis showed this to be a new species of Pasteuria which we have called P. hartismeri. Spores of P. hartismeri attach to juveniles of root-knot nematodes infecting a wide range of plants such as mint (Meloidogyne hapla), rye grass (unidentified Meloidogyne sp.) and potato (Meloidogyne fallax).
Subject(s)
Bacteria/genetics , Bacteria/ultrastructure , Spores, Bacterial/ultrastructure , Tylenchoidea/parasitology , Animals , Bacteria/pathogenicity , Base Sequence , Fraxinus/microbiology , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Molecular Sequence Data , Phylogeny , RNA, Bacterial/genetics , RNA, Bacterial/isolation & purification , RNA, Ribosomal, 16S/genetics , RNA, Ribosomal, 16S/isolation & purification , Spores, Bacterial/physiologyABSTRACT
Pasteuria penetrans is an obligate parasite of plant parasitic nematodes and has yet to be grown in vitro. We have cloned the pivotal sporulation gene, spo0A, which is the first whole gene yet to come from this organism. Partial spo0A sequences were also obtained from the related bacteria, Pasteuria ramosa and Alicyclobacillus acidocaldarius. Phylogenetic analyses using the spo0A sequence data from this and previous studies confirmed the closeness of the genera Pasteuria and members of the supergenus Bacillus. A segment of the spo0A gene was also used to show that genetic heterogeneity exists within and between populations of P. penetrans. This may explain, partly at least, the variability of P. penetrans as a biological control agent of nematodes.
