Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, EpiSciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Molecular evolution of the nicotinic acid requirement within the Shigella/EIEC pathotype.

Abstract : Nicotinamide adenine dinucleotide (NAD) is a crucial cofactor in several anabolic and catabolic reactions. NAD derives from quinolinic acid (QUIN) which in Escherichia coli is obtained through a pyridine salvage pathway or a de novo synthesis pathway. In the latter case, two enzymes, L-aspartate oxidase (NadB) and quinolinate synthase (NadA), are required for the synthesis of QUIN. In contrast to its E. coli ancestor, Shigella spp., the causative agent of bacillary dissentery, lacks the de novo pathway and strictly requires nicotinic acid for growth (Nic⁻ phenotype). This phenotype depends on the silencing of the nadB and nadA genes and its pathoadaptive nature is suggested by the observation that QUIN attenuates the Shigella invasive process. Shigella shares the pathogenicity mechanism with enteronvasive E. coli (EIEC), a group of pathogenic E. coli. On the basis of this similarity EIEC and Shigella have been grouped into a single E. coli pathotype. However EIEC strains do not constitute a homogeneous group and do not possess the complete set of characters that define Shigella strains. In this work we have analysed thirteen EIEC strains belonging to different serotypes and originating from different geographic areas. We show that, in contrast to Shigella, only some EIEC strains require nicotinic acid for growth in minimal medium. Moreover, by studying the emergence of the Nic⁻ phenotype in all serotypes of S. flexneri, as well as in S. sonnei and S. dysenteriae, we describe which molecular rearrangements occurred and which mutations are responsible for the inactivation of the nadA and nadB genes. Our data confirm that the genome of Shigella is extremely dynamic and support the hypothesis that EIEC might reflect an earlier stage of the pathoadaptation process undergone by Shigella.
Document type :
Journal articles
Complete list of metadata

Cited literature [46 references]  Display  Hide  Download
Contributor : Istituto Pasteur Fondazione Cenci Bolognetti Connect in order to contact the contributor
Submitted on : Thursday, July 24, 2014 - 12:45:11 PM
Last modification on : Wednesday, November 3, 2021 - 2:18:09 PM
Long-term archiving on: : Tuesday, April 11, 2017 - 5:49:32 PM


 Restricted access
To satisfy the distribution rights of the publisher, the document is embargoed until : jamais

Please log in to resquest access to the document




Maria Letizia Di Martino, Rosa Fioravanti, Giada Barbabella, Gianni Prosseda, Bianca Colonna, et al.. Molecular evolution of the nicotinic acid requirement within the Shigella/EIEC pathotype.. International journal of medical microbiology : IJMM, 2013, 303 (8), pp.651-61. ⟨10.1016/j.ijmm.2013.09.007⟩. ⟨pasteur-01044923⟩



Record views