Biology subjects

Donnenberg, M. S.

Publications and source records attributed to Donnenberg, M. S..

3 recordsLinked to original sources

bioRxiv2024

Revolutionizing Molecular Cloning: Introducing FastCloneAssist, a Streamlined Python Tool for Optimizing Primer Design in Restriction & Ligation-Independent PCR Cloning

FastCloning, a paradigm shift in PCR cloning, has streamlined the process by eliminating laborious, multi-step traditional methods. This innovative technique, pioneered by Li et al. (2011), utilizes overlapping PCR primers and DpnI digestion for seamless integration of insert DNA into any desired vector position, regardless of restriction sites. This versatility makes FastCloning ideal for constructing fusion proteins, chimeric cDNAs, and manipulating genes with unparalleled ease. However, efficient primer design remains a critical hurdle, particularly for newcomers, as errors can lead to failed cloning attempts. To address this bottleneck, we present FastCloneAssist, a user-friendly Python program that automates FastCloning primer design with minimal user input. Users simply provide vector and insert sequences, along with the desired melting temperature (Tm), and FastCloneAssist provides best primer pairs after calculating optimal primer parameters for efficient PCR amplification and seamless DNA integration using established bioinformatics libraries. This open-source, freely available tool simplifies and accelerates cloning, making this powerful technique accessible to researchers of all levels and expediting scientific discovery.

bioengineering↗

bioRxiv2022

Cryo-EM structure of the Type IV pilus extension ATPase from enteropathogenic Escherichia coli

Type 4 pili (T4P) are retractable surface appendages found on numerous bacteria and archaea that play essential roles in various microbial functions, including host colonization by pathogens. An ATPase is required for T4P extension, but the mechanism by which chemical energy is transduced to mechanical energy for pilus extension has not been elucidated. Here we report the cryo-electron microscopy (cryo-EM) structure of the BfpD ATPase from enteropathogenic Escherichia coli (EPEC) in the presence of either ADP or a mixture of ADP and AMP-PNP. Both structures, solved at 3 [A] resolution, reveal the typical toroid shape of AAA+ ATPases and unambiguous six-fold symmetry. This six-fold symmetry contrasts with the two-fold symmetry previously reported for other T4P extension ATPase structures, all of which were from thermophiles and solved by crystallography. In the presence of the nucleotide mixture, BfpD bound exclusively AMP-PNP and this binding resulted in a modest outward expansion in comparison to the structure in the presence of ADP, suggesting a concerted model for hydrolysis. De novo molecular models reveal a partially open configuration of all subunits where the nucleotide binding site may not be optimally positioned for catalysis. ATPase functional studies reveal modest activity similar to that of other extension ATPases, while calculations indicate that this activity is insufficient to power pilus extension. Our results reveal that, despite similarities in primary sequence and tertiary structure, T4P extension ATPases exhibit divergent quaternary configurations. Our data raise new possibilities regarding the mechanism by which T4P extension ATPases power pilus formation.

microbiology↗

bioRxiv2020

Investigation of the in vitro and in vivo activity of the type IV pilus extension ATPase BfpD

Type IV pili (T4Ps) are multifunctional protein fibers found in many bacteria and archaea. All T4P systems have an extension ATPase, which provides the energy required to push structural subunits out of the membrane. We previously reported that the BfpD T4P ATPase from enteropathogenic E. coli (EPEC) has the expected hexameric structure and ATPase activity, the latter enhanced by the presence of the N-terminal cytoplasmic domains of its partner proteins BfpC and BfpE. In this study, we further investigated the kinetics of the BfpD ATPase. Despite high purity of the proteins, the reported enhanced ATPase activity was found to be from (an) ATPase(s) contaminating the N-BfpC preparation. Furthermore, although two mutations in highly conserved bfpD sites led to loss of function in vivo, the purified mutant proteins retained some ATPase activity, albeit less than the wild-type protein. Therefore, the observed ATPase activity of BfpD was also affected by (a) contaminating ATPase(s). Expression of the mutant bfpD alleles did not interfere with BfpD function in bacteria that also expressed wild-type BfpD. However, a similar mutation of bfpF, which encodes the retraction ATPase, blocked the function of wild-type BfpF when both were present. These results highlight similarities and differences in function and activity of T4P extension and retraction ATPases in EPEC.

microbiology↗