Ogataea parapolymorpha DL-1 Genome sequencing

This project presents a comprehensive genome re-assembly of the methylotrophic yeast, Ogataea parapolymorpha DL-1, utilizing advanced long-read sequencing technology provided by Oxford Nanopore Technologies. The primary objective was to enhance the existing short-read assembly by resolving complex genomic regions, such as repetitive sequences and structural variations, which remained ambiguous or incomplete in the previous assembly. The application of long-read sequencing facilitated the generation of a telomere-to-telomere (T2T) assembly and revealed significant genomic extensions, including the accurate annotation of subtelomeric regions and the identification of multiple rRNA gene copies previously undetected.The new assembly highlights extended chromosome lengths across all chromosomes, affirming the addition of genomic material previously unresolved. Notably, the assembly is characterized by completeness, with a gapless sequence that contrasts sharply with the unfinished chromosomes and inaccuracies reported in the previous short-read assembly. Comparative analysis pinpointed breakpoints in assembly-to-assembly alignment coinciding with gaps in the prior assembly, particularly within chromosomes 1 and 4. Moreover, a detailed annotation of rRNA genes revealed a remarkable amplification of rRNA gene copies in the new assembly, highlighting four copies of each rRNA gene type located in a previously missing subtelomeric region of chromosome 1. This contrasts with the single copy of each gene identified in the short-read assembly, showcasing the long-read assembly's superiority in capturing repeat expansions and complex genomic regions.One of the hallmark findings from this study is the absence of 5-methylcytosine (5mC) modifications within the genome, a discovery that underscores the organism's unique epigenetic landscape. This finding, validated through comparison with a control E. coli genome known for cytosine modifications, points to an evolutionary trajectory wherein Ogataea parapolymorpha DL-1 may have discarded the 5mC methylation system without detrimental effects on its survival or functionality.