A putative transport protein is involved in citrulline excretion and reuptake during arginine deiminiase pathway activity by Lactobacillus sakei

T. RIMAUX; A. RIVIERE; E. HÉBERT; F. MOZZI; S. WECKX; L. DE VUYST; F. LEROY

RESEARCH IN MICROBIOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 164 p. 216 - 225

0923-2508

Arginine conversion through the arginine deiminase (ADI) pathway is a common metabolic trait for strains of the species Lactobacillus sakei and is encoded by an arc operon. In this study, an additional gene [formerly encoded as a putative transport protein (PTP)] was found to be part of the arc operon of L. sakei CTC 494. This gene showed 100% sequence identity with a putative amino acid transporter downstream of the arc operon in L. sakei 23K. A knock-out mutant of L. sakei CTC 494, impaired in the PTP gene, lacked the ability to convert extracellular citrulline into ornithine, indicating that this PTP gene encodes a citrulline/ornithine antiporter. Expression of the PTP gene was modulated by environmental pH and was highest in the end-exponential or mid-exponential growth phase for L. sakei CTC 494 and 23K, respectively. In contrast to the other genes of the arc operon, the PTP gene showed the lowest expression level at pH 7.0, in agreement with the finding that no detectable citrulline-into-ornithine conversion took place at this pH. Besides pH and growth phase, the presence of additional energy sources also influenced ADI pathway activity, in particular by decreasing citrulline-into-ornithine conversion.