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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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Thierry FRANZA



+33 1 3465 2080

mail : Thierry FRANZA

Research subject:

     Streptococcus agalactiae or Group B Streptococcus (GBS) is a human commensal bacterium that can become a pathogen. In addition to direct effects of virulence factors, active aerobic respiratory metabolism has a role in the GBS infection process. GBS encodes a CydA CydB cytochrome bd quinol oxidase for respiration, which is activated by exogenously heme and (demethyl)menaquinone. Respiratory metabolism diminishes oxidative and acid stress from the environment and improves long-term survival of GBS. GBS lacks the men genes implicated in synthesis of the polar headgroup of menaquinone (1,4-dihydroxy-2-naphthoic acid, DHNA). However, GBS possess a homolog of the MenA 1,4-dihydroxy-2-naphthoate prenyltransferase enzyme, involved in the synthesis of menaquinone. Furthermore, GBS encodes an ispB gene (gbs1783) involved in the synthesis of isoprenoid chains. In the presence of DHNA, we showed that GBS is able to synthesize long chain demethylmenaquinones (DMK-10) that are cofactors of the CydA CydB terminal oxidase that also requires exogenous heme to be active (Franza et al., 2016).

Thierry MenA

Thus, through interspecies metabolic exchanges, GBS may be able to switch from fermentation towards a respiratory metabolism that increases its growth capacity and virulence in the host. DHNA is also a redox toxic compound: high concentrations of DHNA inhibit GBS growth. How GBS does cope with this molecule is under study. Control and regulation of respiration is also investigated.

Thierry resp



Bibliography (2015-2018):

Lencina AM, Franza T, Sullivan MJ, Ulett GC, Ipe DS, Gaudu P, Gennis RB, Schurig-Briccio LA.(2018).Type 2 NADH Dehydrogenase Is the Only Point of Entry for Electrons into the Streptococcus agalactiae Respiratory Chain and Is a Potential Drug Target. MBio. 9(4). pii: e01034-18. doi: 10.1128/mBio.01034-18.

Franza, T., Delavenne, E., Derré-Bobillot, A., Juillard, V., Boulay, M., Demey, E., Vinh, J., Lamberet, G., Gaudu, P. (2016). A partial metabolic pathway enables group b streptococcus to overcome quinone deficiency in a host bacterial community. Molecular Microbiology, 102 (1), 81-91



- J Vinh - laboratoire de Spectrométrie de Masse Biologique et Protéomique (USR 3149) de l’ESPCI Paris.

- V Juillard - MICALIS ComBac.

- R Gennis - Department of Biochemistry, University of Illinois, Urbana, USA