RT Journal Article SR Electronic(1) A1 Dávila-Martínez, Yadira A1 Ramos-Vega, Ana Laura A1 Contreras-Martínez, Sandra A1 Encarnación, Sergio A1 Geiger, Otto A1 López-Lara, Isabel M.YR 2010 T1 SMc01553 is the sixth acyl carrier protein in Sinorhizobium meliloti 1021 JF Microbiology, VO 156 IS 1 SP 230 OP 239 DO https://doi.org/10.1099/mic.0.033480-0 PB Microbiology Society, SN 1465-2080, AB Acyl carrier proteins (ACPs) are required for the transfer of acyl intermediates during fatty acid and polyketide syntheses. In Sinorhizobium meliloti 1021 there are five known ACPs: AcpP, NodF, AcpXL, the ACP domain in RkpA and SMb20651. The genome sequence of S. meliloti 1021 also reveals the ORF SMc01553, annotated as a putative ACP. smc01553 is part of a 6.6 kb DNA region that is duplicated in the chromosome and in the pSymb plasmid, the result of a recent duplication event. SMc01553 overexpressed in Escherichia coli was labelled in vivo with [3H]β-alanine, a biosynthetic building block of the 4′-phosphopantetheine prosthetic group of ACPs. The purified SMc01553 was modified with 4′-phosphopantetheine in the presence of S. meliloti holo-ACP synthase, and this modification resulted in a major conformational change of the protein structure, since the holo-form runs faster in native PAGE than the apo-form. SMc01553 could not be loaded with a malonyl group by malonyl-CoA-ACP transacylase from S. meliloti. Using RT-PCR we could show the presence of mRNA for SMc01553 and of the duplicated ORF SMb22007 in cultures of S. meliloti. However, a mutant in which the two duplicated regions were deleted did not show any different phenotype with respect to the wild-type in the free-living or symbiotic lifestyle., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.033480-0