Expression of acyl-CoA-binding protein 5 fromRhodnius prolixusand its inhibition by RNA interference.

Muriel G M D Almeida,Katia C Gondim,Nils J Færgeman,Daniela S Arêdes,David Majerowicz,Jens Knudsen,Yara M Traub-Csekö

doi:10.1371/journal.pone.0227685

Muriel G M D Almeida, Katia C Gondim + Show 5 more

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https://doi.org/10.1371/journal.pone.0227685

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Abstract

The acyl-CoA-binding proteins (ACBP) act by regulating the availability of acyl-CoA in the cytoplasm and must have essential functions in lipid metabolism. The genome of the kissing-bug Rhodnius prolixus encodes five proteins of this family, but little is known about them. In this study we investigated the expression and function of RpACBP-5. Feeding induced RpACBP-5 gene expression in the posterior midgut, and an increase of about four times was observed two days after the blood meal. However, the amount of protein, which was only detected in this organ, did not change during digestion. The RpACBP-5 gene was also highly expressed in pre-vitellogenic and vitellogenic oocytes. Recombinant RpACBP-5 was shown to bind to acyl-CoA of different lengths, and it exhibited nanomolar affinity to lauroyl-CoA in an isothermal titration assay, indicating that RpACBP-5 is a functional ACBP. RpACBP-5 knockdown by RNA interference did not affect digestion, egg laying and hatching, survival, or accumulation of triacylglycerol in the fat body and oocytes. Similarly, double knockdown of RpACBP-1 and RpACBP-5 did not alter egg laying and hatching, survival, accumulation of triacylglycerol in the fat body and oocytes, or the neutral lipid composition of the posterior midgut or hemolymph. These results show that RpACBP-5 is a functional ACBP but indicate that the lack of a detectable phenotype in the knockdown insects may be a consequence of functional overlap of the proteins of the ACBP family found in the insect.

Highlights

Acyl-CoA binding proteins (ACBP) are considered the central protein family that binds esterified fatty acids (FA), acting in the subtle control of their intracellular concentration
Feeding induced RpACBP-5 gene expression in the posterior midgut (Fig 2A) in a pattern that resembles the expression response described for the RpACBP-1 gene [18]
RpACBP-1 mRNA levels were observed in the first day post-feeding, followed by a progressive decrease until the fourth day, when the level of expression was similar to that found in fasting insects [19]

Summary

Introduction

Acyl-CoA binding proteins (ACBP) are considered the central protein family that binds esterified fatty acids (FA), acting in the subtle control of their intracellular concentration. These proteins form a gene family containing proteins of different sizes which present an acyl-CoAbinding domain [1]. ACBPs are highly conserved in all species of eukaryotes and prokaryotes hitherto analyzed, and they are predominantly cytosolic proteins that bind acyl-CoAs in a non-covalent and reversible way. They have high affinity and specificity for medium- and long-chain saturated or unsaturated acyl-CoAs, with Kd varying from 1 to 15 nM [2].

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