MIP diversity from Trichoderma: Structural considerations and transcriptional modulation during mycoparasitic association with Fusarium solani olive trees

Abstract

Major intrinsic proteins (MIP) are characterized by a transmembrane pore-type architecture that facilitates transport across biomembranes of water and a variety of low molecular weight solutes. They are found in all parts of life, with remarkable protein diversity. Very little is known about MIP from fungi. And yet, it can legitimately be stated that MIP are pivotal molecular components in the privileged relationships fungi enjoy with plants or soil fauna in various environments. To date, MIP have never been studied in a mycoparasitism situation. In this study, the diversity, expression and functional prediction of MIP from the genus Trichoderma were investigated. Trichoderma spp. genomes have at least seven aquaporin genes. Based on a phylogenetic analysis of the translated sequences, members were assigned to the AQP, AQGP and XIP subfamilies. In in vitro and in planta assays with T. harzianum strain Ths97, expression analyses showed that four genes were constitutively expressed. In a mycoparasitic context with Fusarium solani, the causative agent of fusarium dieback on olive tree roots, these genes were up-regulated. This response is of particular interest in analyzing the MIP promoter cis-regulatory motifs, most of which are involved in various carbon and nitrogen metabolisms. Structural analyses provide new insights into the possible role of structural checkpoints by which these members transport water, H2O2, glycerol and, more generally, linear polyols across the membranes. Taken together, these results provide the first evidence that MIP may play a key role in Trichoderma mycoparasitism lifestyle.

Chitin and chitosan remodeling defines vegetative development and Trichoderma biocontrol

“…Given their expression during vegetative development and self-recognition in the confrontation assays, they might be involved in distinguishing the own cell wall from that of the host fungus. CDA4 and CDA6 are highly homologous, which is a strong evidence for gene duplication that increases genetic variability and may contribute to adaptability in a changing environment [119]. However, we were not able to delete cda4, pointing at a different but yet crucial role of this gene in vegetative development.…”

Fungal X-Intrinsic Protein Aquaporin from Trichoderma atroviride: Structural and Functional Considerations

“…This matter, regarded as the molecular building blocks of life, is of prime importance in the context of nutrition (metabolism) as well as for maintaining cell homeostasis, osmoregulation and turgor, and determining the final shape of the cells. The MIP superfamily from the Trichoderma genus includes the fungal aquaporins (AQPs) ( stricto sensu ) with the “orthodox fungal water channels”, the fungal aquaglyceroporins (AQGPs) with the Fps -like aquaglyceroporins and the facultative fungal aquaporins (or “other” aquaglyceroporins), and the presumed fungal (un-)orthodox aquaporins X -intrinsic protein (XIP) ( Figure 1 and Figures S1–S3 ) [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68…”

“…In order to access the atomic details of water transport through T. atroviride XIP, a homology model of its three-dimensional structure was built following the same process as in our previous work [ 28 ]. However, this time, the model was integrated into an atomic system mimicking the cellular conditions encountered by this transmembrane protein family (i.e., inserted in a lipidic bilayer and solvated with water and 150 mM KCl ions) and molecular dynamics were performed.…”

“…Total RNA was extracted from mycelia after being ground to a fine powder in liquid nitrogen and treated with a CTAB extraction buffer (Bromide Cetyltrimethylammonium) as previously described [ 28 ]. RNA concentrations were determined by spectrophotometry at OD 260/280 (spectrophotometer ND-1000, Nanodrop, France), and quality was checked by using 2% TAE/agarose electrophoresis.…”

“…This fourth group, XIP, resembles orthodox aquaporins. It is predominantly shared between certain clades of fungi and Viridiplantae, and marginally present in some protozoa [ 26 , 27 , 28 , 29 , 30 , 31 ]. So far, XIP has been found to be the only MIP subgroup common to both plants and mycetes, implying a particular evolutionary relationship between these two unrelated phylogenetic lineages that needs to be resolved.…”