Carvia-Hermoso, C.; Cuéllar, V.; Bernabéu-Roda, L.M.; van Dillewijn, P.; Soto, M.J. Sinorhizobium meliloti GR4 Produces Chromosomal- and pSymA-Encoded Type IVc Pili That Influence the Interaction with Alfalfa Plants. Plants2024, 13, 628.
Carvia-Hermoso, C.; Cuéllar, V.; Bernabéu-Roda, L.M.; van Dillewijn, P.; Soto, M.J. Sinorhizobium meliloti GR4 Produces Chromosomal- and pSymA-Encoded Type IVc Pili That Influence the Interaction with Alfalfa Plants. Plants 2024, 13, 628.
Carvia-Hermoso, C.; Cuéllar, V.; Bernabéu-Roda, L.M.; van Dillewijn, P.; Soto, M.J. Sinorhizobium meliloti GR4 Produces Chromosomal- and pSymA-Encoded Type IVc Pili That Influence the Interaction with Alfalfa Plants. Plants2024, 13, 628.
Carvia-Hermoso, C.; Cuéllar, V.; Bernabéu-Roda, L.M.; van Dillewijn, P.; Soto, M.J. Sinorhizobium meliloti GR4 Produces Chromosomal- and pSymA-Encoded Type IVc Pili That Influence the Interaction with Alfalfa Plants. Plants 2024, 13, 628.
Abstract
Type IVc Pili (T4cP), also known as Tad or Flp pili, are long thin microbial filaments, which are made-up of small-sized pilins. These appendages serve different functions in bacteria including attachment, biofilm formation, surface sensing, motility, and host colonization. Despite their relevant role in diverse microbial lifestyles, knowledge about T4cP in bacteria that establish symbiosis with legumes, collectively referred to as rhizobia, is still limited. Sinorhizobium meliloti contains two clusters of T4cP-related genes: flp-1 and flp-2, which are located on the chromosome and pSymA megaplasmid, respectively. Bundle-forming pili associated to flp-1 have been involved in competitive nodulation of alfalfa plants but the role of flp-2 remains elusive. In this work, we have performed a comprehensive bioinformatic analyses of T4cP genes in the highly competitive S. meliloti strain GR4 and investigated the role of its flp clusters in pilus biogenesis, motility and in the interaction with alfalfa. Single and double flp cluster mutants were constructed in the wild-type genetic background as well as in a flagellaless derivative strain. Our data demonstrate that both chromosomal and pSymA flp clusters are functional in pili biogenesis, and contribute to surface translocation and nodule formation efficiency of GR4. In this strain, the presence of flp-1 in the absence of flp-2 reduces competitiveness for nodule occupation.
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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