Biology subjects

Hüttmann, N.

Publications and source records attributed to Hüttmann, N..

2 recordsLinked to original sources

bioRxiv2026

Post-assembly proteostasis of the respiratory chain is independent of respirasome organization

Respirasomes have long been proposed to stabilize their constituent complexes. Yet the close relationship between individual complex biogenesis and respirasome formation has made it difficult to determine whether respirasomes are required for complex maintenance after assembly. Here, we uncoupled these processes using a genetic perturbation of the CI-CIII2 contact site that severely depletes respirasomes while preserving individual complex assembly and function. Across orthogonal measures of protein stability, turnover and solubility, respiratory-chain maintenance remained largely preserved despite severe respirasome depletion in mouse embryonic fibroblasts, even under mitochondrial stress. We further tested whether a requirement for respirasomes emerges in vivo when OXPHOS biogenesis is progressively impaired through tissue-specific TFAM deletion. Respirasome depletion did not accelerate the loss of CI, CIII2 or CIV during disease progression. Together, our findings show that respirasomes are not a major determinant of post-assembly respiratory-chain complex maintenance, even when mitochondrial homeostasis and OXPHOS biogenesis are challenged.

cell biology↗

bioRxiv2025

Deep-learning deconvolution and segmentation of fluorescent membranes for high-precision bacterial cell-size profiling

Evolutionary studies in bacteria have emphasized genetic and metabolic diversity, while cell-size variation has received less attention. Here we introduce MEDUSSA, a high-throughput method for precise bacterial cell-size profiling based on automatic segmentation of fluorescent membrane images, well suited to studying cell-size diversity. The approach uses deep-learning-based membrane deconvolution, segmentation models fine-tuned for fluorescent-membrane images, and error-corrected cell measurement to extract accurate sizes from individual bacterial cells regardless of shape, size, chaining, or clustering. Our method overcomes limitations of phase-contrast segmentation, yielding reliable single-cell dimensions. We applied MEDUSSA to six strains of Priestia megaterium and found over twofold differences in cell volume across strains, largely driven by differences in cell width. We identified a partially-functional PBP1 allele that underlies the reduced width of one strain. Together, these results demonstrate the power of comparative analyses in bacterial cell biology and expand the toolkit to investigate the evolution of bacterial cell size.

cell biology↗