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Functional diversity of isoprenoid lipids in Methylobacterium extorquens PA1
Author(s) -
Rizk Sandra,
Henke Petra,
SantanaMolina Carlos,
Martens Gesa,
Gnädig Marén,
Nguyen Ngoc Anh,
Devos Damien P.,
NeumannSchaal Meina,
Saenz James P.
Publication year - 2021
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14794
Subject(s) - biology , carotenoid , hopanoids , phytoene , biochemistry , phytoene synthase , terpenoid , chromoplast , squalene , methylobacterium , phytoene desaturase , biosynthesis , chloroplast , gene , plastid , lycopene , paleontology , 16s ribosomal rna , structural basin , source rock
Hopanoids and carotenoids are two of the major isoprenoid‐derived lipid classes in prokaryotes that have been proposed to have similar membrane ordering properties as sterols. Methylobacterium extorquens contains hopanoids and carotenoids in their outer membrane, making them an ideal system to investigate the role of isoprenoid lipids in surface membrane function and cellular fitness. By genetically knocking out hpnE and crtB we disrupted the production of squalene and phytoene in M. extorquens PA1, which are the presumed precursors for hopanoids and carotenoids respectively. Deletion of hpnE revealed that carotenoid biosynthesis utilizes squalene as a precursor resulting in pigmentation with a C 30 backbone, rather than the previously predicted canonical C 40 phytoene‐derived pathway. Phylogenetic analysis suggested that M. extorquens may have acquired the C 30 pathway through lateral gene transfer from Planctomycetes. Surprisingly, disruption of carotenoid synthesis did not generate any major growth or membrane biophysical phenotypes, but slightly increased sensitivity to oxidative stress. We further demonstrated that hopanoids but not carotenoids are essential for growth at higher temperatures, membrane permeability and tolerance of low divalent cation concentrations. These observations show that hopanoids and carotenoids serve diverse roles in the outer membrane of M. extorquens PA1.