Final Destination? Pinpointing Hyella disjuncta sp. nov. PCC 6712 (Cyanobacteria) Based on Taxonomic Aspects, Multicellularity, Nitrogen Fixation and Biosynthetic Gene Clusters

Abstract

Unicellular cyanobacteria inhabit a wide range of ecosytems and can be found throughout the phylum offering space for taxonomic confusion. One example is strain PCC 6712 that was described as Chlorogloea sp. (Nostocales) and later assigned to the genus Chroococcidiopsis (Chroococcidiopsidales). We now show that this strain belongs to the order Pleurocapsales and term it Hyella disjuncta based on morphology, genome analyses and 16S-23S ITS rRNA phylogeny. Genomic analysis indicated that H. disjuncta PCC 6712 shared about 44.7% orthologue genes with its closest relative H. patelloides. Furthermore, 12 cryptic biosynthetic gene clusters (BGCs) with potential bioactivity, such as a mycosporine-like amino acid BGC, were detected. Interestingly, the full set of nitrogen fixation genes was found in H. disjuncta PCC 6712 despite its inability to grow on nitrogen-free medium. A comparison of genes responsible for multicellularity was performed, indicating that most of these genes were present and related to those found in other cyanobacterial orders. This is in contrast to the formation of pseudofilaments—a main feature of the genus Hyella—which is weakly expressed in H. disjuncta PCC 6712 but prominent in Hyella patelloides LEGE 07179. Thus, our study pinpoints crucial but hidden aspects of polyphasic cyanobacterial taxonomy.

An updated classification of cyanobacterial orders and families based on phylogenomic and polyphasic analysis

“…In Hyella , the thallus is composed of irregularly clustered cells branched by pseudodichotomous rows of cells in uniseriate distal parts (Jung et al. 2021b). Baeocytes formed in enlarged cells in the thallus were reported frequently within this group.…”

“…Pleurocapsa forms irregular or radial rows of cells, either uni or multiseriate, sometimes irregularly and pseudodichotomously branched (Brito et al 2017. In Hyella, the thallus is composed of irregularly clustered cells branched by pseudodichotomous rows of cells in uniseriate distal parts (Jung et al 2021b). Baeocytes formed in enlarged cells in the thallus were reported frequently within this group.…”

Biossíntese de metabólitos fotoprotetores em cianobactérias isoladas do Pantanal brasileiro

“…"homólogo de D-Ala-D-Ala ligase" (Miyamoto et al, 2014), "ATP-grasp ligase" (Shimura et al, 2015) e "Shinorina sintetase" (Goswani et al, 2015). Desde então até as publicações mais recentes no tema, o gene mysD foi associado majoritariamente a D-Ala-D-Ala ligase (com variações como D-Ala ligase-like e ddl homólogo) em dezenas de artigos (Chen et al, 2021;Dabravolski;Isayenkov, 2022;D'Agostino et al, 2016;Jung et al, 2021;Katoch et al, 2016;Khani-Juyabad et al, 2022;Llewellyn et al, 2020a;Mishra;Sinha, 2022;Mogany et al, 2022;Osborn;Mahmud, 2019;Rosic, 2019;Shang et al, 2018;Zhang et al, 2021). observando os substratos de mysD e obedecendo as regras de nomenclatura vigentes da enzimologia, este trabalho sugere a utilização da terminologia "micosporina-glicina-amina ligase", uma vez que a reação envolve uma molécula de micosporina-glicina que recebe diferentes aminoácidos através de seus grupos amina.…”