All three domains of life have an ordered plasma membrane which is pivotal in the selective fitness of primitive life. Like cholesterol in eukaryotes, hopanoids are important in bacteria to modulate membrane order. Hopanoids are pentacyclic triterpenoid lipids biosynthesised in many eubacteria, few ferns and lichens. Hopanoid modulates outer membrane order and hopanoid deficiency results in the weakened structural integrity of the membrane which may in turn affect the other structures within or spanning the cell envelope and contributing to various membrane functions. Hence, to decipher the role of hopanoid, genome-wide transcriptome of wild-type and Δshc mutant of Rhodopseudomonas palustris TIE-1 was studied which indicated 299 genes were upregulated and 306 genes were downregulated in hopanoid deficient mutant, representing ∼11.5% of the genome. Thirty-eight genes involved in chemotaxis, response to stimuli and signal transduction were differentially regulated and impaired motility in hopanoid deficient mutant showed that hopanoid plays a crucial role in chemotaxis. The docking study demonstrated that diguanylate cyclase which catalyses the synthesis of secondary messenger exhibited the capability to interact with hopanoids and might be confederating in chemotaxis and signal transduction. Seventy-four genes involved in membrane transport were differentially expressed and cell assays also explicit that the multidrug transport is compromised in Δshc mutant. Membrane transport is reliant on hopanoids which may explain the basis for previous observations linking hopanoids to antibiotic resistance. Disturbing the membrane order by targeting lipid synthesis can be a possible novel approach in developing new antimicrobials and hopanoid biosynthesis could be a potential target.

生命的所有三个领域都有序的质膜，这对原始生命的选择适应性至关重要。像真核生物中的胆固醇一样，类胡萝卜素在细菌中也很重要，可以调节膜的秩序。类胡萝卜素是在许多真细菌，少数蕨类植物和地衣中生物合成的五环三萜类脂质。类蛇菊碱可调节外膜的顺序，类蛇菊碱的缺乏会导致膜的结构完整性减弱，进而可能影响细胞膜内或跨膜的其他结构并有助于各种膜的功能。因此，为了破译hopanoid，野生型的基因组范围的转录和Δ的作用SHC的突变体沼泽红假单胞菌研究了TIE-1，该基因在类hopanoid缺陷型突变体中代表299个基因上调，而306个基因下调，约占基因组的11.5％。38种参与趋化性，对刺激的反应和信号转导的基因受到差异性调控，并且在类hopanoid缺陷型突变体中，运动能力受损表明，hopanoid在趋化性中起着至关重要的作用。对接研究表明，催化次生信使合成的双鸟苷酸环化酶具有与类胡桃糖相互作用的能力，并可能在趋化性和信号转导中发挥作用。差异表达了74个参与膜转运的基因，细胞分析也明确表明Δshc损害了多药转运突变体。膜运输依赖类胡萝卜素，这可能解释了以前的发现将类胡萝卜素与抗生素耐药性联系起来的基础。通过靶向脂质合成来扰乱膜的顺序可能是开发新的抗菌剂的一种可能的新方法，而类胡萝卜素的生物合成可能是潜在的目标。