Biochemical and structural analysis of marine polysaccharide lyases

Abstract

This study investigated marine bacterial PLs capable of degrading the anionic algal polysaccharides alginate and ulvan, respectively. A particular focus was given to (i) an alginolytic system in Alteromonas macleodii 83-1 and (ii) a putative polysaccharide utilization locus for ulvan in Formosa agariphila KMM3901 . The alginolytic system in Alteromonas macleodii 83-1 was studied by producing its five Alys as recombinant proteins, which were expressed in E. coli, and purified via chromatography in order to investigate enzyme activity and kinetics. In addition, phylogenetic analysis was done as well as protein crystallization to solve the enzyme structure of PL7-1. This project is part of the work of Dr. Wietz who is doing culture-based and genomic studies on Alteromonas macleodii 83-1. The analysis of a polysaccharide utilization locus for ulvan in Formosa agariphila T KMM3901 is part of collaboration between the MPI Bremen and the University of Greifswald. Our colleagues from Greifswald are currently working on enzyme kinetics and activity, whereas we contributed the structural analysis of an undescribed ulvan lyase. Our work included protein purification and analytical chromatography, determination of thermal stability, and X-ray crystallography. The present study provides detailed insights into the biochemistry, evolution and functionality of PLs from F. agariphila and A. macleodii with focus on PL7-1 (alginate), as well as PL24 and PL25 (ulvan). Studying the utilization pathways of marine heterotrophic bacteria capable of degrading reduced carbon compounds such as algal polysaccharides contributes to the understanding of processes that considerably impact marine food web dynamics and carbon cycling in the oceans.