Mycosporine-alanine, an oxo-mycosporine, protect Hassallia byssoidea from high UV and solar irradiation on the stone monument of Konark.

Abstract

Mycosporine-like amino acids (MAAs) are small natural molecules having potent UV-absorbing and antioxidant properties. Hassallia byssoidea is one dominant cyanobacterium found all over the Konark stone monument, a UNESCO World Heritage site. We characterized mycosporine-alanine for the first time from H. byssoidea and studied its biosynthetic pathway from the whole genome data. We found D-alanyl-D-alanine carboxypeptidase, which might convert mycosporine-glycine to mycosporine-alanine by replacing glycine with alanine or by separate methylation, the mycosporine-glycine is converted to mycosporine-alanine. Our in vitro UV-B exposure experiment and exposure of H. byssoidea to natural sunlight show an increase in biosynthesis of mycosporine-alanine with 12h of UV-B irradiation and high natural sunlight. We also found mycosporine-alanine to have good free radical scavenging activity with an IC50 value of 1.98mg/ml. Our results show due to the presence of mycosporine-alanine H. byssoidea probably tolerate the UV and high solar radiation and continue to colonize on the Konark stone monument as a dominant cyanobacterium.