Phytoplasmoses of conifers

Fitoplazme su prokarioti bez stanične stijenke te kao biljni patogeni uzrokuju bolesti biljaka diljem svijeta. S vrlo malenim genomom, od 530 do 1350 kb, prosječne su veličine od 200 do 800 nm. Nedostaju im važni geni koji sudjeluju u važnim metaboličkim putevima, kao što su (I) F0F1-ATP–sintaza, geni uključeni u put pentoza fosfata, (II) biosintezu aminokiselina i masnih kiselina, (III) metabolizam aminokiselina, nukleotida, šećera te (IV) geni zaduženi za fiksaciju CO2. Fitoplazme biljku putuju floemom kroz sitaste elementne, gdje sve potrebne nutrijente crpe iz floemskog soka. Do danas je dokazano prisustvo nekoliko različitih sojeva fitoplazmi kod golosjemenjača - ‘Ca. P. pini’, X-disease fitoplazma iz 16S rIII grupe, ‘Ca. P. trifolii’ i ‘Ca. P. phoenicum’. U Hrvatskoj, ‘Ca. P. pini’ prisutna je u dvije vrste bora, Pinus mugo i P. halepensis. Jednom inficirane, biljke pokazuju različite simptome, kao što su virescencija, filodija, vještičja metla te žućenje listova. Fitoplazme uzrokuju velike ekonomske gubitke na različitim biljnim vrstama. Posljedice infekcije golosjemenjača fitoplazmama za sada nisu poznate. Unatoč tome, znanstvenici upozoravaju kako bi fitoplazme mogle predstavljati prijetnju drvnoj industriji. Pretpostavlja se da nakon infekcije fitoplazmama, drveće postaje podložnije gljivičnim infekcijama i/ili različitim nepovoljnim abiotičkim čimbenicima.Phytoplasmas are plant endocellular parasites spread through the world. They range in size from 200 to 800 nm. Their genome is very small, from 530 kb to 1350 kb. Phytoplasmas lack a number of genes involved in: (I) essential metabolic pathways, like F0F1-type ATP–synthase and pentose phosphate pathway, (II) biosynthesis of amino and fatty acids, (III) metabolism of amino acids, nucleotides, sugars, glyoxylate and (IV) CO2 fixation. In plants they reside in sieve elements and move around through the sieve pores, where plant’s sap provides nutrients. To this date, few ‘Ca. Phytoplasma species’ have been detected in gymnosperms - ‘Ca. P. pini’, X disease phytoplasma from 16S rIII group, ‘Ca. P. trifolii’ and ‘Ca. P. phoenicum’. In Croatia, ‘Ca. P. pini’ is detected in two pine species Pinus mugo and P. halepensis. Infected plants exhibit number of symptoms which include shoot proliferation (whiches’ broom), stunting, leaf yellowing, phyllody and dwarfing. Due to phytoplasma infection economic losses in the production of many plant species are substantial. So far, impact and possible consequences of phytoplasma infection in conifers are not known. However, scientists do warn that phytoplasma presence in conifers might present a threat to timber industry. It is thought that phytoplasma infection causes trees to be more vulnerable to infection with fungi and/or other damaging abiotic factors

Phytoplasmoses of conifers

Fitoplazme su prokarioti bez stanične stijenke te kao biljni patogeni uzrokuju bolesti biljaka diljem svijeta. S vrlo malenim genomom, od 530 do 1350 kb, prosječne su veličine od 200 do 800 nm. Nedostaju im važni geni koji sudjeluju u važnim metaboličkim putevima, kao što su (I) F0F1-ATP–sintaza, geni uključeni u put pentoza fosfata, (II) biosintezu aminokiselina i masnih kiselina, (III) metabolizam aminokiselina, nukleotida, šećera te (IV) geni zaduženi za fiksaciju CO2. Fitoplazme biljku putuju floemom kroz sitaste elementne, gdje sve potrebne nutrijente crpe iz floemskog soka. Do danas je dokazano prisustvo nekoliko različitih sojeva fitoplazmi kod golosjemenjača - ‘Ca. P. pini’, X-disease fitoplazma iz 16S rIII grupe, ‘Ca. P. trifolii’ i ‘Ca. P. phoenicum’. U Hrvatskoj, ‘Ca. P. pini’ prisutna je u dvije vrste bora, Pinus mugo i P. halepensis. Jednom inficirane, biljke pokazuju različite simptome, kao što su virescencija, filodija, vještičja metla te žućenje listova. Fitoplazme uzrokuju velike ekonomske gubitke na različitim biljnim vrstama. Posljedice infekcije golosjemenjača fitoplazmama za sada nisu poznate. Unatoč tome, znanstvenici upozoravaju kako bi fitoplazme mogle predstavljati prijetnju drvnoj industriji. Pretpostavlja se da nakon infekcije fitoplazmama, drveće postaje podložnije gljivičnim infekcijama i/ili različitim nepovoljnim abiotičkim čimbenicima.Phytoplasmas are plant endocellular parasites spread through the world. They range in size from 200 to 800 nm. Their genome is very small, from 530 kb to 1350 kb. Phytoplasmas lack a number of genes involved in: (I) essential metabolic pathways, like F0F1-type ATP–synthase and pentose phosphate pathway, (II) biosynthesis of amino and fatty acids, (III) metabolism of amino acids, nucleotides, sugars, glyoxylate and (IV) CO2 fixation. In plants they reside in sieve elements and move around through the sieve pores, where plant’s sap provides nutrients. To this date, few ‘Ca. Phytoplasma species’ have been detected in gymnosperms - ‘Ca. P. pini’, X disease phytoplasma from 16S rIII group, ‘Ca. P. trifolii’ and ‘Ca. P. phoenicum’. In Croatia, ‘Ca. P. pini’ is detected in two pine species Pinus mugo and P. halepensis. Infected plants exhibit number of symptoms which include shoot proliferation (whiches’ broom), stunting, leaf yellowing, phyllody and dwarfing. Due to phytoplasma infection economic losses in the production of many plant species are substantial. So far, impact and possible consequences of phytoplasma infection in conifers are not known. However, scientists do warn that phytoplasma presence in conifers might present a threat to timber industry. It is thought that phytoplasma infection causes trees to be more vulnerable to infection with fungi and/or other damaging abiotic factors

A SAM-key domain required for enzymatic activity of the Fun30 nucleosome remodeler

Fun30 is the prototype of the Fun30-SMARCAD1-ETL subfamily of nucleosome remodelers involved in DNA repair and gene silencing. These proteins appear to act as single-subunit nucleosome remodelers, but their molecular mechanisms are, at this point, poorly understood. Using multiple sequence alignment and structure prediction, we identify an evolutionarily conserved domain that is modeled to contain a SAM-like fold with one long, protruding helix, which we term SAM-key. Deletion of the SAM-key within budding yeast Fun30 leads to a defect in DNA repair and gene silencing similar to that of the fun30Δ mutant. In vitro, Fun30 protein lacking the SAM-key is able to bind nucleosomes but is deficient in DNA-stimulated ATPase activity and nucleosome sliding and eviction. A structural model based on AlphaFold2 prediction and verified by crosslinking-MS indicates an interaction of the long SAM-key helix with protrusion I, a subdomain located between the two ATPase lobes that is critical for control of enzymatic activity. Mutation of the interaction interface phenocopies the domain deletion with a lack of DNA-stimulated ATPase activation and a nucleosome-remodeling defect, thereby confirming a role of the SAM-key helix in regulating ATPase activity. Our data thereby demonstrate a central role of the SAM-key domain in mediating the activation of Fun30 catalytic activity, thus highlighting the importance of allosteric activation for this class of enzymes