Invasion gene associated RNA (also known as InvR) is a small
non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally imp ...
involved in regulating one of the major outer
cell membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...
porin proteins in ''
Salmonella
''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...
'' species.
InvR was originally predicted by computational screening the genome of ''
Salmonella typhimurium
''Salmonella enterica'' subsp. ''enterica'' is a subspecies of ''Salmonella enterica'', the rod-shaped, flagellated, aerobic, Gram-negative bacterium. Many of the pathogenic serovars of the ''S. enterica'' species are in this subspecies, includin ...
'' for novel
sRNA genes.
In this screen 46 candidate sRNA
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
s not conserved in ''
Escherichia coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...
'' were identified.
The ''Salmonella'' the
virulence
Virulence is a pathogen's or microorganism's ability to cause damage to a host.
In most cases, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its abili ...
factors that facilitate invasion of the host intestinal
epithelium
Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...
are located in a ~ 40 kb region in the ''Salmonella'' genome referred to as Salmonella pathogenicity Island 1 (SPI-1). The gene encoding InvR is located in this SPI-1 region between two genes called and STM2901. InvR appears to be unique to ''Salmonella'' species as there does not appear to be any predicted
homologues in other
Enterobacteriaceae
Enterobacteriaceae is a large family (biology), family of Gram-negative bacteria. It includes over 30 genera and more than 100 species. Its classification above the level of Family (taxonomy), family is still a subject of debate, but one class ...
species.
InvR is ~80nt long and appears to be independently expressed from its own
promoter.
Its expression is activated by the transcription factor HilD and has been shown to be abundantly expressed during
exponential growth
Exponential growth occurs when a quantity grows as an exponential function of time. The quantity grows at a rate directly proportional to its present size. For example, when it is 3 times as big as it is now, it will be growing 3 times as fast ...
.
InvR has been shown to bind the RNA chaperone Hfq in vitro and Hfq is required for in vivo stability.
In ''S. typhimurium'' InvR RNA has been shown to repress the synthesis of the abundant outer membrane porin protein OmpD. Despite being located in the SPI-1 region there has been no link identified between the function of InvR and the SPI-1 dependent secretion pathway or invasion.
See also
*
Spi-1 (PU.1) 5′ UTR regulatory element
The Spi-1 (PU.1) 5′ UTR regulatory element is an RNA element found in the 5′ UTR of Spi-1 mRNA which is able to inhibit the translation Spi-1 transcripts by 8-fold. Spi-1 regulates myeloid gene expression during haemopoietic development. ...
References
External links
* {{Rfam, id=RF01384, name=Invasion_gene_associated_RNA_(InvR)
Non-coding RNA