PROTECTIVE EFFECT OF PHASIN PhaP FROM Azotobacter sp.FA-8 AND ITS COMPARISON WITH THE CHAPERONE GroELS

PETTINARI JULIA M; MEZZINA MARIELA P; ALVAREZ DANIELA S

San Miguel de Tucumán

Congreso; XII Congreso Argentino de Microbiología General SAMIGE; 2017

SAMIGE Asociación Civil de Microbiología General

Phasin PhaP from Azotobacter sp.FA-8 is a polyhydroxyalkanoate (PHA) granule-associated proteinthat not only plays an important structural role in polymer accumulation, but has also been shown tohave an unexpected protective effect in non-PHA synthesizing Escherichia coli. This protective effectwas observed under both normal and stress conditions, resulting in increased growth and higherresistance to both heat shock and superoxide stress by paraquat. Moreover, PhaP has chaperoneactivity and was observed to exert a beneficial effect in E. coli cells producing heterologous proteins,playing an active role in protein folding and/or unfolding prevention that reduced the number and sizeof inclusion bodies. Further research showed that PhaP enhanced bacterial fitness in the presence ofbiofuels, such as ethanol and butanol, and to other chemicals, such as 1,3-propanediol. The effect ofPhaP was also studied in a groELS mutant strain, in which both GroELS and PhaP were observed toexert a beneficial effect on cells. These results indicated that PhaP was able to complement thephenotypic effects caused by the groEL mutation in a similar manner as the GroELS protein.In view of these findings, we further studied the ability of PhaP to reduce the impact of different typesof stressors in recombinant E. coli and compared this protection with the known chaperone GroELS.To test if PhaP reduces osmotic stress, a groELS mutant strain, carrying plasmids pBBR1 (control),pADP2 (expressing phaP) and pGroELS1 (expressing groELS), was grown in LB mediumsupplemented with 0,3 M NaCl. As it was observed previously for biofuels, both PhaP and chaperoneGroELS were able to protect cells from high salt concentration. Moreover, the phaP expressing straindisplayed faster growth than the strain overexpressing groELS.Taken together, these results show that PhaP protects cells from multiple stresses, expanding theapplications of the multitalented phasins and opening the road for the development of more resistantstrains, suitable for the synthesis of diverse biotechnologically relevant products from renewablecarbon sources.