Natural rubber ( @entity34643 ) is an indispensable biopolymer used to manufacture diverse consumer products. Although a major source of natural rubber is the rubber tree ( @entity15543 ), lettuce ( @entity12681 ) is also known to synthesize natural rubber. Here, we report that an unusual cis-prenyltransferase-like 2 (CPTL2), which lacks the conserved motifs of conventional cis-prenyltransferase, is required for natural rubber biosynthesis in lettuce. CPTL2, identified from the lettuce rubber particle proteome, displays homology to a @entity1 NogoB receptor and is predominantly expressed in latex. Multiple transgenic lettuces expressing CPTL2-RNAi constructs showed that decrease of CPTL2 transcripts (3-15% CPTL2 expression relative to controls) coincided with the reduction of natural rubber as low as 5%. We also identified a conventional cis-prenyltransferase 3 (CPT3), exclusively expressed in latex. In subcellular localization studies using fluorescent proteins, cytosolic CPT3 was re-localized to endoplasmic reticulum by co-occurrence of CPTL2 in @entity286 and @entity375 at the log phase. Furthermore, yeast two-hybrid data showed that CPTL2 and CPT3 interact. @entity375 microsomes containing CPTL2/CPT3 showed enhanced synthesis of short cis-polyisoprenes, but natural rubber could not be synthesized in vitro. Intriguingly, a homologous pair CPTL1/ @entity13513 , which displays ubiquitous expressions in lettuce, showed a potent @entity56580 biosynthetic activity in vitro. Taken together, our data suggest that CPTL2 is a scaffolding protein that tethers CPT3 on endoplasmic reticulum and is necessary for natural rubber biosynthesis in planta, but @entity375 -expressed CPTL2 and CPT3 alone could not synthesize high molecular weight natural rubber in vitro.

A lettuce ( XXXX ) homolog of @entity1 Nogo-B receptor interacts with cis-prenyltransferase and is necessary for natural rubber biosynthesis.

@entity1 :: ('9606', 'Species') :: ['human'] @entity286 :: ('4097', 'Species') :: ['tobacco'] @entity56580 :: ('MESH:D004286', 'Chemical') :: ['dolichol'] @entity13513 :: ('1374', 'Gene') :: ['CPT1'] @entity34643 :: ('CHEBI:53406', 'Chemical') :: ['cis-1,4-polyisoprene'] @entity12681 :: ('4236', 'Species') :: ['Lactuca sativa'] @entity15543 :: ('3981', 'Species') :: ['Hevea brasiliensis'] @entity375 :: ('4932', 'Species') :: ['yeast', 'Yeast']
@entity12681 :: (4236,Species) :: ['Lactuca sativa']
