{"id":9135,"date":"2024-03-25T14:57:50","date_gmt":"2024-03-25T13:57:50","guid":{"rendered":"https:\/\/www.afmb.univ-mrs.fr\/?p=9135"},"modified":"2024-04-04T13:03:30","modified_gmt":"2024-04-04T12:03:30","slug":"the-work-of-katy-tamburrini-sonia-longhi-and-their-collaborators-are-highlighted-by-cnrs-biologie-congratulations","status":"publish","type":"post","link":"https:\/\/www.afmb.univ-mrs.fr\/en\/2024\/03\/25\/the-work-of-katy-tamburrini-sonia-longhi-and-their-collaborators-are-highlighted-by-cnrs-biologie-congratulations\/","title":{"rendered":"The work of Ketty Tamburrini, Sonia Longhi and their collaborators is highlighted by CNRS Biologie, congratulations!"},"content":{"rendered":"\n

A new mechanism involved in cellulose degradation by a phytopathogenic fungus<\/h2>\n\n\n\n

In an article published in the journal PNAS, scientists describe a mechanism used by a phytopathogenic fungus to “boost” cellulose degradation during plant infection. The discovery of this process could pave the way for the production of new enzymatic cocktails to degrade cellulose, a polymer abundant on Earth and a source of energy but highly resistant to degradation.<\/p>\n\n\n\n

Plant pathogenic fungi (phytopathogens) have the ability to degrade plant cell walls containing cellulose during the infection process. Some of the enzymes involved in cellulose degradation have peculiarities that have caught the attention of scientists. Indeed, these enzymes have regions that are “intrinsically disordered”, meaning they lack a unique and precise three-dimensional structure. These regions, possessing a constantly changing structure, are nevertheless capable of exerting a biological function precisely because of this lack of fixed structure. Their malleability allows them to establish interactions with many partners, and this promiscuity enables them to regulate functions in numerous biological processes.<\/p>\n\n\n\n

Studying a widespread fungal disease significantly impacting the yield of vegetable, fruit, and cereal crops<\/h3>\n\n\n\n

An exhaustive bioinformatic analysis of 27,060 sequences of these enzymes, called Lytic Polysaccharide MonoOxygenases (LPMOs), revealed that these disordered appendices were widespread among these enzymes. The prevalence of these disordered regions, whose function was unknown and neglected by the scientific community, in enzymes from highly divergent organisms in terms of evolution hinted at an important functional role. Scientists then undertook the study of these enigmatic regions in phytopathogenic fungi of the genus Colletotrichum, responsible for anthracnose, a widespread fungal disease significantly impacting the yield of vegetable, fruit, and cereal crops. To penetrate plant tissues, these fungi have evolved over hundreds of millions of years to acquire the ability to degrade polymers such as cellulose. They use specialized enzymes, such as LPMOs, for this purpose.<\/p>\n\n\n\n

During this study, scientists focused on LPMOs belonging to the AA9 family of the fungus Colletotrichum orbiculare. Through a bioinformatics approach, regions predicted to be disordered at one end of these LPMOs were identified, and two of these enzymes were then selected for studying these enigmatic extensions. These two fungal enzymes were subsequently produced by recombinant means in yeast, an organism capable of manufacturing proteins similar to, or identical to, those produced by Colletotrichum. The disordered nature of these regions was confirmed using biophysical methods such as small-angle X-ray scattering, a technique particularly suitable for studying flexible systems.<\/p>\n\n\n\n

New enzymatic cocktails to more effectively degrade cellulose<\/h3>\n\n\n\n

Unexpectedly, these enzymes were found to be capable of dimerization, and scientists demonstrated that this dimerization process confers enhanced properties to these enzymes in terms of substrate binding and cellulose activity. Dimerization relies on the formation of a disulfide bridge involving a cysteine residue located in the disordered extension. Thus, these disordered regions, which were previously systematically eliminated before any structural and functional study of LPMOs, turned out to be more than simple appendices and are essential for the formation of enzyme dimers with higher enzymatic activity compared to the monomeric form.<\/p>\n\n\n\n

The results also show that the dimerization process is not a simple artifact occurring in a test tube containing purified enzyme, as this process also occurs in the fungus C. orbiculare, where this enzyme is indeed secreted in dimer form during infection. Scientists then deciphered the role of this enzyme in the plant penetration mechanism: eliminating this enzyme in C. orbiculare results in a defect in appressorium formation, the specialized structure for penetrating plant tissues.<\/p>\n\n\n\n

Furthermore, scientists have shown that the ability to dimerize is not a unique property of LPMOs from C. orbiculare, and it is also observed in other fungi of the genus Colletotrichum. The findings from this study illustrate the ability of fungi to adapt to their environment by producing enzymes capable of degrading recalcitrant polymers and pave the way for the development of new enzymatic cocktails to more effectively degrade cellulose<\/p>\n\n\n\n

<\/p>\n\n\n\n

\"figure\"\/
\u00a9 Sonia Longhi, Jean-Guy Berrin, Sayo Kodama
Figure : Feuille de concombre infect\u00e9e par le champignon phytopathog\u00e8ne Colletotrichum orbiculare<\/em><\/strong>. Ce champignon secr\u00e8te un cocktail d\u2019enzymes parmi lesquelles figure l\u2019enzyme AA9A, une LPMO de la famille AA9, capable de d\u00e9grader la cellulose, un polym\u00e8re complexe pr\u00e9sente \u00e0 la surface des feuilles. Un conform\u00e8re de cette enzyme \u00e0 l\u2019\u00e9tat dim\u00e9rique est repr\u00e9sent\u00e9 en \u00ab cartoon \u00bb avec un monom\u00e8re en couleur mauve (\u00e0 gauche) et l\u2019autre monom\u00e8re en arc-en-ciel (\u00e0 droite). Le r\u00e9sidu de cyst\u00e9ine, pr\u00e9sent dans l\u2019appendice C-terminal d\u00e9sordonn\u00e9 et impliqu\u00e9 dans la formation du pont disulfure entrainant la dim\u00e9risation de l\u2019enzyme, est montr\u00e9 en sph\u00e8res. L\u2019infection de la plante par la souche sauvage de C. orbiculare (wt) poss\u00e9dant une LPMO AA9A intacte et fonctionnelle, permet une p\u00e9n\u00e9tration efficace de la plante, alors que chez la souche DAA9A, o\u00f9 l\u2019enzyme LPMO AA9A a \u00e9t\u00e9 \u00e9limin\u00e9e, on observe un d\u00e9faut dans la formation de l\u2019appressorium et un nombre r\u00e9duit de hyphes p\u00e9n\u00e9tratives (fl\u00e8ches noires).<\/figcaption><\/figure>\n\n\n\n

En savoir plus :<\/strong>
The disordered C-terminal tail of fungal LPMOs from phytopathogens mediates protein dimerization and impacts plant penetration. <\/a>Tamburrini KC<\/strong>, Kodama S, Grisel S, Haon M, Nishiuchi T, Bissaro B, Kubo Y, Longhi S, Berrin JG. Proc Natl Acad Sci U S A. 2024 Mar 26;121(13):e2319998121. doi: 10.1073\/pnas.2319998121. Epub 2024 Mar 21. PMID: 38513096<\/p>\n\n\n\n

Contact<\/h2>\n\n\n\n

Sonia Longhi<\/p>\n\n\n\n

Directrice de recherche CNRS au laboratoire Architecture et fonction des macromol\u00e9cules biologiques (AFMB)<\/p>\n\n\n\n

+33 4 13 94 95 17<\/a><\/p>\n\n\n\n

sonia.longhi@univ-amu.fr<\/a><\/p>\n\n\n\n

Jean-Guy Berrin<\/p>\n\n\n\n

Chercheur Inrae<\/p>\n\n\n\n

jean-guy.berrin@inrae.fr<\/a><\/p>\n\n\n\n

Laboratoires<\/h3>\n\n\n\n

Architecture et fonction des macromol\u00e9cules biologiques – AFMB<\/strong> (CNRS\/Aix Marseille universit\u00e9)
163, Avenue de Luminy, Case 932
13288 Marseille<\/p>\n\n\n\n

Biodiversit\u00e9 et Biotechnologie Fongiques – BBF <\/strong>(Inrae\/Aix Marseille Universit\u00e9)
163, Avenue de Luminy, Case 925
13288 Marseille<\/p>\n","protected":false},"excerpt":{"rendered":"

A new mechanism involved in cellulose degradation by a phytopathogenic fungus In an article published in the journal PNAS, scientists […]<\/p>\n","protected":false},"author":3,"featured_media":9134,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"class_list":["post-9135","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-informations","entry"],"_links":{"self":[{"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/posts\/9135","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/comments?post=9135"}],"version-history":[{"count":5,"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/posts\/9135\/revisions"}],"predecessor-version":[{"id":9222,"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/posts\/9135\/revisions\/9222"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/media\/9134"}],"wp:attachment":[{"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/media?parent=9135"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.afmb.univ-mrs.fr\/en\/wp-json\/wp\/v2\/categories?post=9135"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}