grown in a defined medium lacking calcium did not exhibit the tetragonally-arranged surface layer present on calcium-sufficient cells, although each cell type possessed equivalent amounts of surface-localized -protein. The addition of Ca or Sr to calcium-limited cells suspended in buffer resulted in formation of the -layer, whereas a similar addition of Mg or Be did not. Incubation of cells with SO during Ca-mediated reassembly of the -layer confirmed that the array was formed from previously synthesized, surface-localized -protein. Rate-zonal sedimentation of -protein extracted from calcium-limited cells demonstrated tetrameric -protein subunits characteristic of the native array. -protein on the surface of calcium-limited cells was not more susceptible to iodination or proteolytic degradation than that on calcium-sufficient cells. These data suggested minimal alteration of the surface layer beyond disorganization of the -protein subunits. Calcium limitation caused only a minor perturbation of the outer membrane and did not prevent the outer membrane from serving as a template for the reassembly of externally supplied -protein subunits. Notably, Mg or Ca mediated reassembly of the -layer and produced a layer that was more loosely attached than the native array. These data support the hypothesis that calcium is specifically required for the assembly of -protein subunits into a tetragonal surface array.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error