Fig. 3

Comparative analysis of amino-acid biosynthesis and provisioning mechanisms in B. tabaci, A. pisum and N. lugens. a Unique amino acid biosynthetic and supply mechanisms putatively related to the adaptation of MED/Q. Green and yellow areas denote bacteriocytes and endosymbiont cells (with respect to the filtered and annotated Portiera genome of MED/Q, PRJNA299729), respectively. Essential amino acids are represented in pink and non-essential amino acids in black; Portiera genes are in blue boxes. The Enzyme Commission numbers (EC) or enzyme names used correspond to those in the Kyoto Encyclopedia of Genes and Genomes (KEGG). MED/Q genes are indicated in red boxes. Black dotted lines represent transport processes between MED/Q and Portiera, and red dotted lines represent processes associated with MED/Q that occur within Portiera bacteriocytes. Candidate horizontally-transferred genes (HTGs) are highlighted in yellow text; white boxes with black text represent unidentified genes. b Comparisons of amino acid biosynthesis in the host-symbiont bacterial systems of B. tabaci-Portiera, A. pisum-Buchnera, and N. lugens-yeast-like organism. Abbreviations: Bt-Bemisia tabaci, Ap-Acyrthosiphon pisum, Nl-Nilaparvata lugens, Pa-Portiera, Ba-Buchnera, Yt-yeast-like. The notation Bt (Ap, Nl, Pa, Ba, or Yt) means that MED/Q alone can complete the amino acid biosynthesis. The notation Bt-Pa (Ap-Ba or Nl-Yt) means that both MED/Q and at least two of its endosymbionts are required to complete the amino acid biosynthetic pathway. c Comparison of key substrates or intermediate products of the host-endosymbiont systems of B. tabaci-Portiera, A. pisum-Buchnera and N. lugens-yeast-like symbiont, illustrating that phosphoenolpyruvic acid (PEP), erythrose-4P, pyruvate, ornithine, and the precursor of histidine synthesis (PRPP) are important for amino acid synthesis. Pyruvate and PEP are produced by glycolysis and erythrose-4P by the pentose phosphate pathway. D-ribose-5P is the substrate for PRPP synthesis, and D-ribose-5P was converted based on D-glyceraldehyde 3-phosphate, also a product of glycolysis. Black arrows with dotted lines represent transport processes between MED/Q and Portiera