Deciphering Pathways for Carotenogenesis in Haloarchaea.

Area of Science:

• Microbiology
• Biochemistry
• Bioinformatics

Background:

• Haloarchaea are known to produce bacterioruberin as their major carotenoid.
• Other carotenoids are synthesized at low concentrations, but carotenogenesis pathways remain controversial.
• Genomic data offers new insights into haloarchaeal carotenoid production capabilities.

Purpose of the Study:

• To construct a hypothetical metabolic map of carotenogenesis in haloarchaea.
• To investigate bacterioruberin synthesis in the *Haloferax* genus.
• To elucidate the carotenoid biosynthesis pathways in halophilic archaea.

Main Methods:

• Bioinformatic analysis of haloarchaeal genomes.
• Comparative genomics to identify carotenogenesis genes.
• Metabolic pathway reconstruction.

Main Results:

• A functioning alternative mevalonic acid (MVA) pathway provides isopentenyl pyrophosphate (IPP) in most analyzed haloarchaea.
• The pathway leads to lycopene synthesis.
• Lycopene serves as a precursor for β-carotene and bacterioruberin, including its derivatives.

Conclusions:

• The alternative MVA pathway is crucial for carotenoid production in haloarchaea.
• Lycopene is a central intermediate in haloarchaeal carotenogenesis.
• This study provides a comprehensive map of carotenoid biosynthesis in haloarchaea.