Researchers identify unique cellsignalling system in some S pneumoniae strains

An article involving Dr Hasan Yesilkaya and Mrs Anfal Shakir Motib, from our Department of Infection, Immunity and Inflammation working with an international team has been listed as this week’s ‘Featured Research Article’ by the journal PLOS Pathogens.

Featured Research are high-quality research articles identified by the Editors-in-Chief as being of particular importance and relevance to the pathogens community and general public.

The paper, ’Promiscuous signaling by a regulatory system unique to the pandemic PMEN1 pneumococcal lineage’, explores how researchers have identified unique cell-signalling system in some S. pneumoniae strains.

S. pneumoniae is widespread in the human respiratory tract, but usually does not cause any symptoms. However, in children and the elderly, it is a major cause of pneumonia, meningitis, and other potentially deadly diseases. Of particular interest is a group of S. pneumoniae strains known as PMEN1, which are pandemic and multi-drug resistant.

The team found that two genes in PMEN1, phrA2 and tprA2, interact to regulate S. pneumoniae gene expression. The protein encoded by tprA2 inhibits expression of phrA2 and other neighbouring genes, including a gene known as lcpA.

In mice, the researchers found, the TprA2 protein does not affect S. pneumoniae colonisation in the nasopharynx, but it does protect against lung infection. The findings suggest that this is a result of TprA2's control over lcpA expression.

Phylogenetic analysis suggests that the genes in the TprA2/PhrA2 system initially found their way into an ancestral PMEN1 strain through horizontal gene transfer, instead of being passed from a dividing cell to its daughter cells. The authors note that this may be the first example of a horizontally transferred regulatory system that has integrated with ancestral network to allow gene regulation across strains.