Tag: prokaryotes

Updated protein family models used by PGAP available for download

Release 3.0 of the NCBI protein family models used by the Prokaryotic Genome Annotation Pipeline (PGAP) is now available from our FTP site. You can search this collection of hidden Markov models (HMMs) against your favorite prokaryotic proteins to identify their function using the HMMER sequence analysis package.

The 3.0 release contains 17,350 models: 12,864 HMMs built at NCBI (111 more than in release 2.0) and 4,486 TIGRFAM HMMs. In addition, since release 2.0,  we have assigned product names to over 2,000 Pfam HMMs, bringing the total to 6,698 Pfam HMMs with names that can be transferred by PGAP to the annotated proteins they hit. You can access a table of these product names from the release directory.Prot_evidenceFigure 1. The evidence for name assignment for type III secretion system (T3SS) translocon subunit SctB (NF038055) showing the protein matches. Species-specific names for this highly variable component of T3SS include YopD, EspB, IpaC, SipC, etc. Instead, we used the standard moniker for core genes of T3SS, Sct, Secretion and cellular translocation (PMID 26520801,  PMID 9618447) providing a unified nomenclature for this secretion system.  Continue reading “Updated protein family models used by PGAP available for download”

Enhanced prokaryote type strain report now with details on needed type strain data

The Prokaryote type strain report provides information on type-strains for over 18,000 species. We revised and expanded the report to make it easier to identify cases where sequencing or establishing type material would have the biggest impact on improving prokaryote taxonomy and accurate identification.  These cases include species with designated type strains but without a sequenced type strain assembly and species without designated type material. We hope that the community will prioritize sequencing type strains for the former set of species (Table 1) and establishing a neotype or reftype, where applicable (as defined in Cuifo et al 2018) for the latter set (Table 2).

Other changes from the old format file are detailed in a recent genomes announce post.

Scientific Name Type material/co-identical strains Assemblies
Burkholderia ubonensis CCUG:48852, CIP:1070, … 308
Escherichia albertii Albert 19982, BCCM/LMG:20976, … 181
Xanthomonas perforans AATCC:BAA-983, DSM:18975, … 153
Listeria innocua ATCC:33090, BCCM/LMG:11387, … 106
Streptococcus iniae ATCC:29178, BCCM/LMG:14520, … 94
Vibrio lentus CECT:5110, CIP:107166, … 87
Vibrio cyclitrophicus ATCC:700982, BCCM/LMG:21359, … 83
Pseudomonas coronafaciens BCCM/LMG:5060, CFPB:2216, … 77
Aliivibrio fischeri ATCC:7744, BCCM/LMG:4414, … 66
Xanthomonas fragariae ATCC:33239, BCCM/LMG:708, … 61

Table 1. The top 10 candidate species for sequencing type-strains sorted by the number of assemblies. These have designated type strains but no type strain assembly. We generated the list by sorting by “number of assemblies from type materials per species”, then by decreasing “number of assemblies per taxon”, then filtering out “type materials and coidentical strains” = “na”.

Table 2. The top 10 candidates for proposing a reftype assembly, or neotype where applicable sorted by the number of assemblies. These species have no designated type strain.  We generated the list by selecting for “type materials and coidentical strains” = “na”, “number of assemblies from type materials per species” = 0, and sorting by decreasing “number of assemblies per taxon”, then filtering out Candidatus.

Please contact info@ncbi.nlm.nih.gov if you want to provide information about missing type-strains.

Expanded average nucleotide identity analysis now available for prokaryotic genome assemblies

As we described in an earlier post, GenBank uses average nucleotide identity (ANI) analysis to find and correct misidentified prokaryotic genome assemblies. You can now access ANI data for the more than 600,000 GenBank bacterial and archaeal genome assemblies through a downloadable report (ANI_report_prokaryotes.txt) available from the genomes/ASSEMBLY_REPORTS area of the FTP site. The README describes the contents of the report in detail. You can use the ANI data to evaluate the taxonomic identity of genome assemblies of interest for yourself.

The new ANI_report_prokaryotes.txt replaces the older ANI_report_bacteria.txt in the same directory. We are no longer updating the ANI_report_bacteria.txt file and will remove it after 31st May 2020.

New release of the Prokaryotic Genome Annotation Pipeline with updated tRNAscan and protein models

A new version of the Prokaryotic Genome Annotation Pipeline (PGAP) is now available on GitHub. This release uses a new and improved version of tRNAscan (tRNAscan-SE:2.0.4) and includes our most up-to-date Hidden Markov Model and BlastRule collections for naming proteins.

Remember that you can submit the results of PGAP to GenBank. Or, if you are still improving the assembly and your genome doesn’t pass the pre-annotation validation, you can use the –ignore-all-errors mode to get a preliminary annotation.

See our previous post and our documentation for details on how to set up and run PGAP yourself.

Try PGAP and let us know how you like it!

Expanded accession formats appear in RefSeq release 93

Expanded accession formats appear in RefSeq release 93

RefSeq release 93 is accessible online, via FTP and through NCBI’s Entrez programming utilities, E-utilities.

This full release incorporates genomic, transcript, and protein data available as of March 13, 2019. It contains 192,722,653 records, including 135,670,032 proteins, 25,840,272 RNAs, and sequences from 88,816 organisms.

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Improved search for prokaryotic assemblies and genes

We now have many improvements to our search functionality on NCBI’s global search page that will benefit users trying to find prokaryotic assemblies and genes. These improvements aim to highlight the best results and provide links to related NCBI content, so you don’t have to sift through pages of results and navigate between different NCBI resources.

new search genome assembly

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How to Download Bacterial Genomes Using the Entrez API

Given the size of modern sequence databases, finding the complete genome sequence for a bacterium among the many other partial sequences can be a challenge. In addition, if you want to download sequences for many bacterial species, an automated solution might be preferable.

In this post we’ll discuss how to download bacterial genomes programmatically for a list of species using the E-utilities, the application programming interface (API) to NCBI’s Entrez system of databases.  We’ll also take advantage of NCBI’s redesigned Genome database, which links all genome sequences for a given species to one record, making it easy to obtain the desired sequences once you find the right Genome record. In principle you can apply the procedure below to other simple genomes that are represented by a single sequence. Future posts will address additional considerations that apply to complex, eukaryotic genomes.

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