PinR mediates the generation of reversible population diversity in Streptococcus zooepidemicus.

The research focuses on how Streptococcus zooepidemicus, an opportunistic pathogen affecting various animals, adapts to diverse environments. Scientists discovered that a serine recombinase, PinR, enables the pathogen to alter its surface makeup, thus enhancing its survival chances in varying conditions.

Understanding the Research

• The research explores how opportunistic pathogens, particularly Streptococcus zooepidemicus (an organism causing disease in a range of animals including horses and humans), survive and adapt in different environments. This adaptability is important to exploit the versatile lifestyle of these organisms.
• Streptococcus zooepidemicus has the ability to assemble different surface architecture phenotypes from one genotype. This is critical for its successful exploitation in diverse habitats.

Role of PinR in Streptococcus zooepidemicus

• The researchers constructed a series of mutants and observed that a serine recombinase, PinR, inverts 114 base pairs of the promoter of SZO_08560. This promoter is bounded by inverted GTAGACTTTA and TAAAGTCTAC repeats. A promoter is a region of DNA that initiates the transcription of a particular gene.
• The inversion caused by PinR acts a switch, controlling the transcription of a sortase-processed protein, which may enhance the attachment of the pathogen to the trachea of horses.

Analysis of Strain Sz2329 and PinR’s Influence

• The genome of a recently sequenced strain of S. zooepidemicus, 2329 (Sz2329), was found to have an internal inversion of the FimIV pilus locus. This strain lacks pinR and this inversion may have become irreversible following the loss of this recombinase.
• Active inversion of FimIV was detected in three strains of S. zooepidemicus, 1770 (Sz1770), B260863 (SzB260863) and H050840501 (SzH050840501), all of which encoded pinR. A deletion mutant of Sz1770 that lacked pinR was no longer capable of inverting its internal region of FimIV.
• The data suggests that PinR can reversibly influence the wider surface architecture of S. zooepidemicus, providing this organism with a solution (bet-hedging) to survive in fluctuating environments.

Acknowledging the Redundancy in PinR Sequence Recognition

• The study also acknowledges redundancy in the PinR sequence recognition motif around a short TAGA consensus, meaning that multiple sequences can be recognized and inverted by PinR. This redundancy gives the organism the flexibility to adapt its surface architecture under changing environments, enhancing its chances of survival.