Cargo Genes of Tn
            <i>7</i>
            -Like Transposons Comprise an Enormous Diversity of Defense Systems, Mobile Genetic Elements, and Antibiotic Resistance Genes

Benler, Sean; Faure, Guilhem; Altae-Tran, Han; Shmakov, Sergey; Feng, Zhenghe; Koonin, Eugene V.

doi:10.1128/mbio.02938-21

Cited by 47 publications

(25 citation statements)

References 135 publications

(174 reference statements)

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“…This is in line with the fact that even with closely related elements (i.e., within the I-F3 CRISPR-Cas elements) ends can diverge sufficiently to allow them to be orthogonal ( Klompe et al, 2022 ). This orthogonality is required for evolving the vast diversity of Tn7-like elements ( Benler et al, 2021 ).…”

Section: Resultsmentioning

confidence: 99%

Structural basis of transposon end recognition explains central features of Tn7 transposition systems

Kaczmarska¹,

Czarnocki-Cieciura²,

Górecka-Minakowska³

et al. 2022

Molecular Cell

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Section: Resultsmentioning

confidence: 99%

Structural basis of transposon end recognition explains central features of Tn7 transposition systems

Kaczmarska¹,

Czarnocki-Cieciura²,

Górecka-Minakowska³

et al. 2022

Molecular Cell

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“…However, the domains involved in binding undergo different structural variations to accomplish the specific protein-DNA interactions for each transposase. This diversity could be required to accommodate the sequences of a large number of Tn7-like elements, preventing transposases from recognizing DNA sequences belonging to other transposons 31 .…”

Section: Resultsmentioning

confidence: 99%

Structure of the TnsB transposase-DNA complex of type V-K CRISPR-associated transposon

et al. 2022

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CRISPR-associated transposons (CASTs) are mobile genetic elements that co-opted CRISPR-Cas systems for RNA-guided transposition. Here we present the 2.4 Å cryo-EM structure of the Scytonema hofmannii (sh) TnsB transposase from Type V-K CAST, bound to the strand transfer DNA. The strand transfer complex displays an intertwined pseudo-symmetrical architecture. Two protomers involved in strand transfer display a catalytically competent active site composed by DDE residues, while other two, which play a key structural role, show active sites where the catalytic residues are not properly positioned for phosphodiester hydrolysis. Transposon end recognition is accomplished by the NTD1/2 helical domains. A singular in trans association of NTD1 domains of the catalytically competent subunits with the inactive DDE domains reinforces the assembly. Collectively, the structural features suggest that catalysis is coupled to protein-DNA assembly to secure proper DNA integration. DNA binding residue mutants reveal that lack of specificity decreases activity, but it could increase transposition in some cases. Our structure sheds light on the strand transfer reaction of DDE transposases and offers new insights into CAST transposition.

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Section: Dna Binding By Shtnsb Ectnsb and Mua Transposasesmentioning

confidence: 99%

Structure of the TnsB transposase-DNA complex of type V-K CRISPR-associated transposon

Castano

Sofos

López-Méndez

et al. 2022

Preprint

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CRISPR-associated transposons (CASTs) represent unique mobile genetic elements that co-opted CRISPR-Cas immune systems for RNA-guided DNA transposition. Type V-K CAST is composed by Cas12k, TniQ, TnsC and TnsB. Here, we present the 2.46 A cryoelectron microscopy structure of the Scytonema hofmannii CAST TnsB transposase in complex with the strand transfer DNA in a post-catalytic state. The shTnsB strand transfer complex maintains the intertwined architecture of the MuA phage transpososome. However, the building of the assembly depends on different local interactions. The protein-DNA complex forms a pseudo-symmetrical assembly in which the 4 protomers of shTnsB adopt two different conformations. The recognition of the transposon ends is accomplished by two small helical domains. The two protomers involved in the strand transfer reaction display a catalytically competent active site composed by three acidic residues (DDE), while the other two, which play a key role in the complex architecture, show catalytic pockets where the DDE residues are not properly positioned for cleavage. Quantification of in vivo transposition assays of mutants in key DNA binding residues, reveals that the lack of specificity generally decreases activity, but it could increase transposition in some cases. Our structure sheds light on the strand transfer reaction of the DDE DNA transposases and offers new insights into RNA-guided transposition in CAST systems.

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Cargo Genes of Tn 7 -Like Transposons Comprise an Enormous Diversity of Defense Systems, Mobile Genetic Elements, and Antibiotic Resistance Genes

Abstract: Transposons are major vehicles of horizontal gene transfer that, in addition to genes directly involved in transposition, carry cargo genes. However, characterization of these genes is hampered by the difficulty of identification of transposon boundaries.

Cited by 47 publications

References 135 publications

Structural basis of transposon end recognition explains central features of Tn7 transposition systems

Structural basis of transposon end recognition explains central features of Tn7 transposition systems

Structure of the TnsB transposase-DNA complex of type V-K CRISPR-associated transposon

Structure of the TnsB transposase-DNA complex of type V-K CRISPR-associated transposon

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