Joe Peters Lab
@joepeterslab.bsky.social
Professor and Chair, Dept Microbiology Cornell Ithaca. Interested in genome evolution and mobile DNA, especially Tn7 and CRISPR-Cas transposition systems
Great to have former lab member Mike Petassi for a seminar with our Replication, Recombination, and Repair group! Presenting some of his postdoc work in the @dnacurtain.bsky.social lab. cals.cornell.edu/microbiology...
August 11, 2025 at 7:03 PM
Great to have former lab member Mike Petassi for a seminar with our Replication, Recombination, and Repair group! Presenting some of his postdoc work in the @dnacurtain.bsky.social lab. cals.cornell.edu/microbiology...
Exciting work from the Guarné lab indicating how the elusive TnsE pathway of prototypic Tn7 recognizes DNA replication features using an asymmetric dimer to integrate multiple signals at DNA replication forks linking target recognition to transposase recruitment doi.org/10.1093/nar/...
June 15, 2025 at 11:43 AM
Exciting work from the Guarné lab indicating how the elusive TnsE pathway of prototypic Tn7 recognizes DNA replication features using an asymmetric dimer to integrate multiple signals at DNA replication forks linking target recognition to transposase recruitment doi.org/10.1093/nar/...
We could identify pre-insertion sites in Streptomyces genomes which suggest a novel mechanism of guide RNA-directed transposition with this type I-E CAST system that abolishes the protospacer recognized by the system. 6/7
November 15, 2024 at 2:10 PM
We could identify pre-insertion sites in Streptomyces genomes which suggest a novel mechanism of guide RNA-directed transposition with this type I-E CAST system that abolishes the protospacer recognized by the system. 6/7
The two families of telomeric transposons associate with the proteins required for telomere maintenance/conjugation Tpg/Tap/TtrA, suggesting the elements also capture the telomeres, a process that will provide an addiction system ensuring maintenance of the transposon. 5/7
November 15, 2024 at 2:10 PM
The two families of telomeric transposons associate with the proteins required for telomere maintenance/conjugation Tpg/Tap/TtrA, suggesting the elements also capture the telomeres, a process that will provide an addiction system ensuring maintenance of the transposon. 5/7
Streptomyces have linear chromosomes that are covalently bound at their linear ends by proteins. These proteins protect the ends from DNA repair and allow end replication. We identified two families of transposons that occurred in one orientation at the ends of linear chromosomes. 4/7
November 15, 2024 at 2:10 PM
Streptomyces have linear chromosomes that are covalently bound at their linear ends by proteins. These proteins protect the ends from DNA repair and allow end replication. We identified two families of transposons that occurred in one orientation at the ends of linear chromosomes. 4/7
While DNA transposons are known to move using two ends that include the transposase binding sites, these transposons have only one standard transposon end, with the other end being a telomere. 3/7
November 15, 2024 at 2:10 PM
While DNA transposons are known to move using two ends that include the transposase binding sites, these transposons have only one standard transposon end, with the other end being a telomere. 3/7
In cyanobacteria we identified the first example of telomeric transposons as one branch among a type of guide RNA-directed transposons, the type V-K CAST elements. Instead of encoding the Cas12K effector, these elements have a protelomerase. We call these PAST elements. 2/7
November 15, 2024 at 2:10 PM
In cyanobacteria we identified the first example of telomeric transposons as one branch among a type of guide RNA-directed transposons, the type V-K CAST elements. Instead of encoding the Cas12K effector, these elements have a protelomerase. We call these PAST elements. 2/7
Aligning the DNA sequences that flank the ends of the tRNA- and array-targeting elements revealed a conserved DNA motif 40 to 50 bp away from the transposons left ends. 8/n
October 26, 2024 at 6:44 PM
Aligning the DNA sequences that flank the ends of the tRNA- and array-targeting elements revealed a conserved DNA motif 40 to 50 bp away from the transposons left ends. 8/n
Unlike the tRNA-targeting pathway from the closely related McCAST element, the array targeting element was not functinoal in E. coli and may need host factors not found in this heterologous host. 7/n
October 26, 2024 at 6:44 PM
Unlike the tRNA-targeting pathway from the closely related McCAST element, the array targeting element was not functinoal in E. coli and may need host factors not found in this heterologous host. 7/n
AlphaFold3-generated structures of TnsD proteins from A. franciscana (AfTnsD, array-targeting) and M. californica (McTnsD, tRNA-tagreting) suggest that the C-terminal region absent in AfTnsD corresponds to a helix-turn-helix domain (HTH) used for DNA binding. 6/n
October 26, 2024 at 6:43 PM
AlphaFold3-generated structures of TnsD proteins from A. franciscana (AfTnsD, array-targeting) and M. californica (McTnsD, tRNA-tagreting) suggest that the C-terminal region absent in AfTnsD corresponds to a helix-turn-helix domain (HTH) used for DNA binding. 6/n
Unlike most Tn7-like elements, array-targeting transposons do not accumulate cargo genes. This contrasts with what is found even with the closely related tRNA-targeting elements. 5/n
October 26, 2024 at 6:43 PM
Unlike most Tn7-like elements, array-targeting transposons do not accumulate cargo genes. This contrasts with what is found even with the closely related tRNA-targeting elements. 5/n
A distinct structural difference that co-occurs with the change in att site used between these two elements is a C-terminal motif found in the tRNA-targeting TnsD proteins that is absent in the array-targeting group. 4/n
October 26, 2024 at 6:43 PM
A distinct structural difference that co-occurs with the change in att site used between these two elements is a C-terminal motif found in the tRNA-targeting TnsD proteins that is absent in the array-targeting group. 4/n
A similarity tree of nonredundant TnsD/TniQ proteins revealed that the array-targeting transposons are phylogenetically close to TnsD-mediated tRNA-targeting transposons in this phylum, a group that includes validated I-D and I-B2 CAST. 3/n
October 26, 2024 at 6:42 PM
A similarity tree of nonredundant TnsD/TniQ proteins revealed that the array-targeting transposons are phylogenetically close to TnsD-mediated tRNA-targeting transposons in this phylum, a group that includes validated I-D and I-B2 CAST. 3/n
We found a novel family of Tn7-like transposable elements in Cyanobacteria which display a preference for insertion within CRISPR arrays, suggesting a previously unrecognized functional interplay between Tn7-like elements and CRISPR-Cas systems. 2/n
October 26, 2024 at 6:41 PM
We found a novel family of Tn7-like transposable elements in Cyanobacteria which display a preference for insertion within CRISPR arrays, suggesting a previously unrecognized functional interplay between Tn7-like elements and CRISPR-Cas systems. 2/n
Previous work indicates that diverse mobile elements evolved the capacity to recognize replicating DNA on the lagging-strand, some via an interaction with DnaN - Tn7, IS608, and group II introns. LINE-1 in humans interacts with the PCNA replication processivity factor.
August 11, 2024 at 4:06 PM
Previous work indicates that diverse mobile elements evolved the capacity to recognize replicating DNA on the lagging-strand, some via an interaction with DnaN - Tn7, IS608, and group II introns. LINE-1 in humans interacts with the PCNA replication processivity factor.
The cryoEM structure of TnpA from another Tn3-family element Tn4430 was used to model Tn1721 TnpA and indicated the position of the QLxxLR motif. Interaction with DnaN likely helps direct the transposase but is unlikely to be in the final complex used for transposition.
August 11, 2024 at 4:05 PM
The cryoEM structure of TnpA from another Tn3-family element Tn4430 was used to model Tn1721 TnpA and indicated the position of the QLxxLR motif. Interaction with DnaN likely helps direct the transposase but is unlikely to be in the final complex used for transposition.
The expression plasmid was a preferred target for Tn1721 transposition with an apparent bias to promoter regions. Few insertions occurred into the chromosome, but consistent with previous work, these insertions mapped to the region where chromosomal DNA replication terminates.
August 11, 2024 at 4:05 PM
The expression plasmid was a preferred target for Tn1721 transposition with an apparent bias to promoter regions. Few insertions occurred into the chromosome, but consistent with previous work, these insertions mapped to the region where chromosomal DNA replication terminates.
An in vivo transposition assay was developed which showed multiple amino acid positions within the motif were important for transposition. A genetic assay supported the idea that only one protomer in the TnpA dimer needs to interact with DnaN.
August 11, 2024 at 4:04 PM
An in vivo transposition assay was developed which showed multiple amino acid positions within the motif were important for transposition. A genetic assay supported the idea that only one protomer in the TnpA dimer needs to interact with DnaN.
The transposase (TnpA) from Tn3-family element Tn1721 was found to physically interact with DnaN in multiple assays including a bacterial two-hybrid assay. This interaction was dependent on amino acid positions within the QLxxLR motif.
August 11, 2024 at 4:03 PM
The transposase (TnpA) from Tn3-family element Tn1721 was found to physically interact with DnaN in multiple assays including a bacterial two-hybrid assay. This interaction was dependent on amino acid positions within the QLxxLR motif.
DnaN is the sliding clamp processivity factor used in bacterial DNA replication. Bioinformatic analyses of the transposase amino acid sequence indicated a QLxxLR DnaN-binding motif in specific sub-branches of Tn3-family elements.
August 11, 2024 at 4:02 PM
DnaN is the sliding clamp processivity factor used in bacterial DNA replication. Bioinformatic analyses of the transposase amino acid sequence indicated a QLxxLR DnaN-binding motif in specific sub-branches of Tn3-family elements.
We have one in press at Annual Reviews in Biochemistry if you want to send me email, joe.peters@cornell.edu. Natural and engineered guide RNA-directed transposition with CRISPR-Cas associated Tn7-like transposons
December 29, 2023 at 2:22 PM
We have one in press at Annual Reviews in Biochemistry if you want to send me email, joe.peters@cornell.edu. Natural and engineered guide RNA-directed transposition with CRISPR-Cas associated Tn7-like transposons
So great to have a visit from former PhD student Mike Petassi. Also allowed us to celebrate the 3 year anniversary of his exciting first CAST paper this month with co-author Shan-Chi (Popo) Hsieh
December 28, 2023 at 9:16 PM
So great to have a visit from former PhD student Mike Petassi. Also allowed us to celebrate the 3 year anniversary of his exciting first CAST paper this month with co-author Shan-Chi (Popo) Hsieh
This is a very interesting area of study! Multiple Tn7-like elements specifically target competency genes for inactivation. Tn7-like Tn6022 targets comM. In my lab found that multiple Tn7-CRISPR-Cas (aka CAST) elements also target comM or comEC using guide RNAs. doi.org/10.1093/nar/...
November 7, 2023 at 2:23 PM
This is a very interesting area of study! Multiple Tn7-like elements specifically target competency genes for inactivation. Tn7-like Tn6022 targets comM. In my lab found that multiple Tn7-CRISPR-Cas (aka CAST) elements also target comM or comEC using guide RNAs. doi.org/10.1093/nar/...
Great to have Andrew Varble as visiting speaker at Cornell Microbiology. The Peters lab took him out to lunch before sending him back to University or Rochester
November 3, 2023 at 4:59 PM
Great to have Andrew Varble as visiting speaker at Cornell Microbiology. The Peters lab took him out to lunch before sending him back to University or Rochester