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 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 important types of non-c ...
involved in regulating one of the major outer
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
porin proteins in ''
Salmonella
''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type species and is fur ...
'' 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, includi ...
'' for novel
sRNA genes.
In this screen 46 candidate sRNA
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
s not conserved in ''
Escherichia coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'' were identified.
The ''Salmonella'' the
virulence
Virulence is a pathogen's or microorganism's ability to cause damage to a host.
In most, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to ca ...
factors that facilitate invasion of the host intestinal
epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
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 was first proposed by Rahn in 1936, and now includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject ...
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 is a process that increases quantity over time. It occurs when the instantaneous rate of change (that is, the derivative) of a quantity with respect to time is proportional to the quantity itself. Described as a function, a q ...
.
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. Mu ...
References
External links
* {{Rfam, id=RF01384, name=Invasion_gene_associated_RNA_(InvR)
Non-coding RNA